Computer games. I have dozens and dozens of computer games, and must buy the latest and greatest. The problem is that I almost never finish them. I think the last game that I finished was Final Fantasy 7 about 6 years ago.
In the past, books and cross-stitch patterns. I’ve stopped buying patterns, for the most part. Furthur remarked to me once that, if there is an afterlife, I’m going to need it just to stitch all those patterns. He’s right of course, but the dear man doesn’t understand that all patterns must be stitched, and tastes do change… 
Now, my buying obsessions are: peanut butter, paper towels, corn muffin mix, mandarin oranges, and like foodstuff & dry goods. I have 12-15 boxes of cereal in the house for example. This is good now, though, because with Furthur unemployed, we can live on peanut butter, cereal, and mandarin oranges if nothing else. 
Mrs. Furthur
PC and Video games. Must…stop…buying…
Good thing the OP states “irrational”, otherwise I’d be shaking my about some of you.
My props to the book buyers(as long as they arent romance novel :rolleyes: )
OK…mine ?..a $ to the first person who shares this one with me…MUSKIE LURES.
I got a bucktail,crankbait or jerkbait for any situation.
dont worry I’ll be here alot less when fishing season starts again
Kalhoun and zephyrine, are you me? I have to have at least 3 shampoo/conditioner choices. This past summer, this compulsion reached a new height of insanity. I had about six brands at home and wandered down the hair care aisle of CVS, and thought “I haven’t tried Fructis yet and same goes for this Back to Basics stuff.” $30 later, I had 8 shampoos and conditioners. Of course, I rationalize these purchases by insisting that mixing up shampoos and condiitoners helps maintain healthy hair and decrease build-up.
I totally stockpile TP as well. I almost never have fewer than 12 rolls on hand (and I live alone!). I hated the days of being so broke I was forced to resort to stolen fast food napkins.
I also buy books compulsively, particularly Japanese grammar and textbooks. I’m learning Japanese relatively slowly so a lot of the books are above my level but I still feel compelled to buy them.
My most irrational purchase is bar soap. I hate running out, can never remember if I have any, and buy big packs on sale. I just bought two 20 packs (forgetting I actually had two 12 packs squirrelled away) so now I have SIXTY-FOUR bars of soap!! For one relatively small person who takes one shower a day! I figure I’m set for the next few years…
CD’s:
Whether it’s walking into a record store or surfing atMusicStack.com.
It’s a total compulsion. It started in the early 90’ when I started replacing my vinyl. I’d have the same routine every Friday: Go to Tower, buy two replacements & one new title. On top of that, I had a list of rare / OOP stuff that I had to find in the CD format. I’d search high and low - looking everywhere I could to find them. I arranged my travel plans based on international cities that might have hard-to-find titles (like for example - taking a two day layover in London on the way to Oktoberfest - even though I’d never put the Square Mile on the list of my fave Autumn destinations). I finally got my hands on The Howlin Wolf Album in January - it was the last title on my ‘rare list’. CD collection is just under 2000 & should be near 2,100 by Christmas.
Underwear (In Winter Months) & Bathing Suits (In Summer):
Though I’ve never been accused of being a slave to fashion, underwear and swimwear are the only garments I buy on impulse. If I see something I like, I buy it, without any regard to the price tag.
I think the most I ever paid was $49.99 for a pair of underwear.
Bar Ware / Signage:
Even though I get a couple of freebies from my restaurant / tap room business, I can’t stop buy vintage beer signs, mirrors, etc. for the bar I have at home.
I almost paid $1,100 for a rareLite Beer Coast to Coast Sign on E-Bay & I don’t even like Miller. Luckily, someone outbid me and I was able to find the same sign for $400 from a proprietor who owns a chain of bars in the county east of me.
I shop exactly according to the written shopping list, very rarely buying anything on impulse.
This drives my wife nuts, as she is likely to write down “Dinner things” or “School lunch stuff” without specifying what, if anything, she has in mind. This drives ME nuts.
Me: “What dinner things?”
Her: “Oh, you know, just whatever looks good”
Me: “Arg!”
Any kind of beauty and hair products. I never spend very much on one item (the most might be $20 on foundation, and maybe $10 on shampoo) … but before I moved in with McDeath I had two totes full, plus a small suitcase. And that was the stuff I DIDN’T use on a daily basis.
The most irresistible to me … lipliner/lipgloss/lipstick, mascara, foundation … and hair gels/creams/mousses. They don’t sell my favourite Freeman product here anymore, and I’ve been frantically trying to replace it. It’s very sad. 
I’ve managed to throw away a lot of it, mainly for space reasons. But it was hard.
I also buy magazines compulsively - if I had my way, I’d probably buy 4-5 a week.
E-mail me off the board. My address is in my profile.
Books. Lots and lots of books. European History (which I teach). Civil War (which I love to read about). Novels of all sorts. Books, and more books. Even though I read roughly 1000wpm, I still have a “To Read” stack 5 feet high. I just took 5 boxes to the local “Friends of the Library” bookstore. I just can’t help myself. Birds gotta swim, fish gotta fly, I gotta read.
All three of you - get out of my head! I do the same thing. It doesn’t even have to be expensive salon stuff; Walgreen’s or the grocery store is a great place to get a fix… er, I mean buy stuff.
I am addicted to Bath & Body Works shower gels and lotions, but I love trying new shampoos and conditioners, and the cheap stuff like Suave and Fructis is fun to try.
Also, lip balms. I love the Burt’s Bees peppermint oil one, and the old standby Cherry Chapstick, but I love trying new ones. I just got a new one today at Walgreen’s; it’s an organic one, Almond Nut. I have lip balms in every coat pocket, a couple in my purse, and a couple in my car.
I also buy tons of books. I do eventually read them, but if my To-Be Read pile ever fell over on me, you’d need to send in the sniffer dogs to get me out.
Orchids. You know the way some people will see a puppy in the window or a kitten in a box and be unable to go home without it? Well, that’s how it is with me sometimes when I see a certain plant. I may not even find the flower all that special (although to me, all orchid flowers are special). It wouldn’t be that bad, except I don’t have space or money for them since I’m a poor university student. Last month I went to the Pacific Orchid Expo and told myself I would only buy two plants tops…I came home with six.
And books. Used books. Especially cookbooks, out of which I will use perhaps two recepies. Curse you Bogey’s Books! Curse your appealing selection and your willingness to recommend things to me!
For me it’s shoes and purses. I have to force myself to avoid shoe stores or I’ll come out with three pair. At least. I don’t know why I love shoes so much.
Lately I have a thing for lipstick, and have been buying them like crazy. But it is as nothing compared to my obsession with shoes.
How are these things different?
(I’m a guy with short hair- I use the same soap for my body and hair. I’m genuinely curious about what these things are.)
Computer games. I have over a hundred (over two hundred if you count my Commodore stuff) and continually acquire more. Sims 2 will probably be my next purchase.
Lemon Heads and Now and Laters. Luckily they’re only .25 each so it’s not an expensive compulsion. I also eat them all. I consider it irrational bcause I have a weight problem and very sensitive teeth. I almost always hurt my teeth eating these thing and they make my reflux go crazy but I still buy them. It might be hereditary though, my sister does it too.
One of the wierdest things: One of my former coworkers had a tuna obsession. He bought some every time he went shopping and never missed a tuna sale. He had something like 50 cans when I quit that job. At least he ate it.
Here’s a link: Jane’s stuff for sale
Shampoo is for washing your hair. Conditioner is for making your hair soft, manageable, etc. Shower gel is basically liquid soap for washing the rest of you.
I’m a compulsive book shopper, myself - I cannot go into a book store without coming out with at least one book. I have about 15-20 books lined up waiting to read, but I can always buy more.
Underwear, socks, candy, and duct tape. I have about 5 or 6 rolls of duct tape in my room right now, and an endless amount of socks and underwear. Seriously, if I was trapped in my room for a few years, I would still have clean underwear to wear. Socks are just handy to have around. I mean, you need a special pair of socks for St.Patrick’s Day, and Christmas, and all the other holidays, and you need underwear to match…Duct tape is just awesome. I use it for everything. I have candy stashes hidden all around my room, which comes in handy when my brother cooks dinner…