What have you done, that seemed like a good idea and you know regret?
Me? Drinking that 4th red bull and Jaeger
Opening this thread ? 
Getting on a plane in San Jose.
Buying a 125 gallon fish tank and putting it in the living room.
Pulling up perfectly serviceable, if a trifle stained, wall-to-wall carpeting, to find marvelous wood floors underneath, only to realize, too late, that while dirt disappears into carpeting, dirt just lies there on top of the marvelous wood floors, and they have to be SWEPT. Constantly.
Giving Kid #3 a romantic but slightly silly middle name.
Trading in the Old Reliable 1987 Dodge Aries station wagon for a shiny new Dodge Caravan. I want my wagon back! :mad: I can’t fit any groceries in the back of this thing, they just roll around on the floor, and the “bag holder hooks” suck SO BAD.
Not threatening suicide and/or divorce when the Better Half brought home a beagle puppy five years ago.
Does that work?
Majored in aeronautical engineering.
Eating that meatloaf sandwich. (where’s the vomiting smilie when you need one?)
Downloading Tetrinet. Sure, I’ll just play it once in a while. Yeah, right.
Not being able to have Chris over yesterday to watch movies. Oh well, I’ll see if he’s up for shopping at the mall next weekend.
Giving away that old Impala that needed only $20 in repairs to fix it up.
Not beating the crap out of that mouthy guy in school when he finally pushed my buttons hard enough. Years ago.
Giving a new hire an even break, hiring him over several better qualified people because he had a family. Later I discovered he was going behind my back, griping about me and making trouble.
Believing that girl when she said she had not slept with him.
Not dumping that stock when the guy who suggested that I buy it dumped his.
Dumping that stock thinking it had gotten as high as it would go.
…Majoring in Social Work. Ugh.
Taking a 1st grade teaching job fresh out of methodology classes, but before I’d even student taught. That is the definition of baptism by fire. 
Other stuff, too, but I don’t want to depress myself.
I once drank some homemade beer a friend had found in his dad’s garage, where he apparently brewed it regularly.
But my friend had given me a bottle that had new yeast in it.
Most people have not gone in to detail about their bad ideas, so here’s a short story that illustrates several ideas I had in a row, all seemingly good ideas to me at the time. History will no doubt judge them differently!
I don’t know why, but once I was hanging out with my homies in a large appartmentblock and we decided to ignite some terpentine we found.
The best place we could think of for this endevour was the very livingroom where the terpentine was found, it was my friend’s mother’s appartment and was being painted. We put it in a plastic bowl and tried to light it, nothing happened.
So, naturally we put some newspaper into the terpentine and tried again. Yup… that did the trick. Damn near killed us and the rest of the good people living in the house, too! You see, we couldn’t grab the flaming bowl to throw it out the window as planned, 'cause it was too hot!
Everyone was kinda freakin’ out at that point, but I was laughing my ass off, thinking this was the way we were all going to die and how sadly amusing that was (some drugs were probably present, although I think I was sober, I was just a fucked up teenager!).
Eventually I decided to remedy the situation by taking this big metal tool thingy and using it to grab the flaming bowl of terpentine, and then throw it out the window with total disregard as to what was below.
However, things went totally ballistic when I grabbed the bowl (remember it was plastic!). It didn’t only disintegrate, it appeared to detonate in the grasp of this big metal tool I was using, I guess I clasped it together too hard. The result was an impressively erupting fountain of fire and mayhem that did little to end the screaming and genral panicking of the crowd present.
This set fire to much of the livingroom, most notably all the curtains and a large sofa. For some reason this absolutely killed me, I could barely breathe because I was laughing so damn hard! I even collapsed on the burning couch, exhausted from laughter.
My friends managed to put the fires out quite quickly and there was little damage to the apartment. They wanted to do a bit of damage to me though, the laughing was not well received, but they got over it 
I can’t recall what I was thinking: lighting a bowl of terpentine and paper in an apartmentblock! But I do remember that it seemed like a completely reasonable thing to do at the time… Then again, so did a lot of other dumb stuff.
— G. Raven
FTR, burning rubber cement makes remarkably affective (and affordable!) napalm.
1st place.
college, screwdrivers
vodka + orange juice
OJ all gone
vodka + orange Gatoraide™
Gatoraide™ all gone
vodka + tang™! (glass of vodka, 2 scoops of Tang™)
This is what astronauts drink when they want to puke nonstop for a damn long time.
But…it seemed like such a good idea at the time. I don’t think we ever got the marshmallows out of the toaster.
2nd place. Roommate’s new microwave. Me wanting MW popcorn. Me not knowing how long to set said microwave. Me putting popcorn in microwave for 8 minutes, planning to listen for pop every second or so and subtract ramaining time from initial set time (very scientific). Me going into the living room “for a minute” and forgetting about the popcorn. Me smelling the smell of burned popcorn an instant before the microwave “digned” and the smoke alarm went off.
So much for science!
Oooooooo. Ouch.
My brother-in-law (a not-usually-this-stupid kind of guy) had heard that, if you douse your finger with rubbing alcohol, you can light your finger on fire without any real harm. I think the principle was that the alcohol evaporates quickly enough to cool your finger (note: I dunno of this is true, so don’t be tryin’ it on my say-so).
Anyway, for some reason he misheard rubbing alcohol as rubber cement. He stuck some rubber cement on his finger and lit it. As you might expect, the experience was a little more painful than bargained for. He semi-panicked, and started shaking his hand around to cool it. This just sent flaming gobbets of cement arcing through the room, landing (and sticking) on the walls and ceiling. He finally just sat on his hand to put it out.
The flaming gobbets left permanent scorch marks on the walls, but no real damage. My brother-in-law walked around the next few days with a potato on his finger. I thought it was funny, but he was a little less amused.
Buying myself a skateboard for my 35th birthday. I never ride the damn thing.
It is true. When I fill a zippo and want to freak people out at a party, I shake it so that some of the lighter fluid gets onto my finger, which I then use to light my cigarette.
I will not assume responsibility for anyone who damages their digits using this method.
A potato? 
Aw, c’mon. What was the name? Please?
We had stone top tables back in 9th grade chemistry class and we’d rub the little glass bottle burners on the top of the table and then set the alcohol on fire. Once while doing this, the top of my burner came off and I got a bunch on my hand, the flame caught it, and proceed to sit there and watch my hand burn. Actually, I had a couple blisters but it pretty much went out when the alcohol burned off.
Stupid. It hurt too.
My regret: it has something to do with an old boyfriend and I’m goin’ no further than that.