My brother and I, instead of using “good luck”, always moan “pray… for… mojo…” and, when having a snack, “I know I shalt not eat thee… <munch munch>”
and of course the japanese greeting “hello chief let’s talk why not!”
Like TheRob, I use Purple-Monkey-Dishwasher quite a bit, whenever I need a verbal password.
Whenever I return home from the liquor store, I put my purchases on the kitchen counter and anounce “I’m going on the bender to end all benders”, ala Krusty.
My son and I, whenever something is said that sounds remotely like “Moe” will start chanting “Moe…Moe…Moe…”
I occassionally refer to something being less than adequate as “the suckiest bunch of sucks who ever sucked”. I also mentally refer to my son as “my damn weiner kid” but that’s not the sort of thing you can take to the grandparents 
And, of course, there’s my sig…
I used to have my computer set up to quote Homer’s brain–“That’s it, I’m outa here”–when it shut down.
When I am in the presence of food I really like, I will sometimes make Homer’s drooling sound, the one Lisa translated to English as “transcendental”.
When things are just going good for me generally, I say “excellent” in a Burns voice…love overpronouncing the “l” sound 
When things are going bad, I will make the noise sideshow Bob makes when he steps on a rake, and maybe say that I am having a “Sideshow Bob” moment.
When I am experiencing an emotion for which there is no convenient label, I just say “Yarrrr” like the Sea Captain.
In the one episode where Homer owns a racehorse and is threatened by the other jockeys (I’m sure someone will be along shortly to say, “why, that’s 7G14, IDIOT!”, but anyway), there’s the following scene:
Homer(eyes narrowed, menacingly): Don’t worry honey, I’ll get those murderous trolls…
Lisa: What are you talking about?
Homer(snapping back to reality): I mean! … (menacingly again) I’ll get those murderous trolls…
In my circle of friends it’s turned into common usage of “[ridiculous thing]…I mean!..[same ridiculous thing].”
You probably have to be there/have seen the episode, I s’pose.
Well, I don’t know if Bart invented the term “craptacular,” but I’ve begun using it frequently thanks to him.
I have a friend at work with whom I’ve had entire conversations made up of nothing but Simpsons quotes.
Our favorites:
“mmm… sacri-licious…”
“There’s no such thing as Scotchtoberfest!” “WHAT? Ya USED ME!!!”
“Everyone knew it was a scam!” “Willy didna!”
I can’t believe I forgot to mention my constant use of “Excellent…” D’oh!
Anyway, some more:
When my husband suggests turning in for the night: “Oh boy–sleep! That’s where I’m a Viking!” (This is my all-time favorite Ralph-ism)
When trying to convince someone that something ridiculous is actually reasonable: “It’s a perfectly cromulent [reason, excuse, word, whatever].”
My husband and I always call it a “saxamaphone” now, thanks to Homer.
When trying to convince someone to do something and they refuse, my husband will sometimes say, “Darn! I almost had him eating dog food!”
I have a co-worker who, when things really go his way, has been known to utter: “All right! Everything’s coming up Milhouse!”
Anytime I offer to make salad as part of a meal (or when my mother-in-law does), my husband chants, “You don’t win friends with salad…”
There are more, but I can’t think of them right now. And to think, when I met my husband, I didn’t even watch “The Simpsons.”
I always like the “stay back or i’ll spork your ass!” But i think that was from the critic, but it was as good as the simpsons.
I think ralph is me and my friend’s favorite character. “Oh no, i bent my wookie!” “I’m learnding.” “Hi prinskiple skinner, hi super nintendo chalmers.” “MIss hoover, i ate my worm, can i have a new one?” Lol, those always make us laugh.
Yeah, my wife and I do that, too! She reminded me of another one last night, out of thin air: When one of us is confused or bored, we say, “So . . . the cops knew Internal Affairs was setting them up the whole time?”
Also, any sentence that begins with “Guess who . . .?” is inevitably met by, “Is it George Segal? I hear he plays the banjo!”
And usually, whenever we hear someone (like on a roller coaster) yell, “Wheeeeeeeeeee!” we add on “Must . . . kill . . . Moe . . .”
Heh… just remembered another one because I did it today.
Person A: “Who’s going to… (whatever)?”
Me: “I dunno… Coast Guard?”
Of course, you have to say “I dunno” as something like “iunno”
I just have to that I love that episode, it’s so very silly and bizarre.
“You traded my soul for POGS?”
My very favorite, which I’m proud to say I’ve managed to work into normal conversation, is:
Burns: Now go.
Homer: Or what? You’ll release the dogs, or the bees, or the dogs with bees in their mouths so when they bark they shoot bees at you? Do your worst!
Burns: Smithers, release the robotic Richard Simmons.
Homer screams and runs off as the robot says “Shake shake shake.”
No one ever gets it because the episode it’s from (Bart becomes Mr. Burns’ heir) was aired with a different sequence. I saw this one on one of those anniversary shows the Simpsons does sometimes.
Oh, I get it. I get jokes.
There’s always the chance for a good Simpsons quote.
I’m always amazed at how often “We could have seen a monkey!” seems appropriate - anytime we miss out on doing something that seems stupid but still would have been cool.
“Let’s go crazy, Broadway style” is another favourite for all occasions when about to go out and hit the town.
“My cat’s breath smells of cat food” is a good reply to someone who comes out with a non-sequiter, or just a really strange remark.
I’m studying literature at the moment, so I’ve had a couple of chances to use the “they sure sucked the fun out of that poem” line.
I seem to remember many years ago “Can’t talk, coming down” used to get a bit of use.
“I can’t promise I’ll try, but I promise I’ll try to try” - self explanatory.
And finally, when studying European literature “Boy, those Germans have a word for everything!”
I thought I knew the Simpsons but all of youse seem to have a much better grip on the important things than me.
I will admit that sometimes when alone I hug the TV.
Redboss
I use one from that episode where they go to New York:
My wife: Would you like a bowl of soup?
Me:No bowl…Stick…STICK!!
But that joke only get’s me crab juice instead of Mountain Dew:(
(Mrs. Bietz isn’t a big Simpsons fan:rolleyes: )
One to use while giving our combined vengance to the freaking SDMB hacker: That’ll learn ya to bust my tomato.
I find myself saying both DOH! And the Hank Scorpio line, “Sure homer, sorry it’s not in packets.”
I just LOVE the whole spiel about The Hammock District
I used to work with a guy who did the 4 day weekend thing. He got me hooked on it.
He’d use it for little stuff though, not involving vacations. If we were slow and the manager let him leave early or something, “Whoo hoo! Four day weekend!” If a sandwich would come on the screen and there was already an extra one made, it was a four day weekend.
Now, when I find extra money or something doing my cash, or I find out a drawer’s not really short, it’s a four day weekend.
I use them so often that it has become a running joke. Whe we were first dating, my wife thought I was hilarious. She loved a lot of my running jokes. But when she moved in with me, she started watching the show with me. It seems like every episode she was discovering what a hack I am. Even some of our little couple moments stemmed from simpson lines.
A few faves:
- Column A and B
- “Yeah…think about it…”
- Purple Monkey Dishwasher
- Slack Jawed Yokel
- Sitcheeation (Moe’s pronunciation of situation)
- I was hoping ta do ya (Moe’s reason for wanting a date to go well)
- Sleep. That’s where I’m a viking
- When I grow up, I am going to Bovine University
- So this is what it feels like, When Doves cry.
- You’re talking crazy talk.
- We’re also absolved if the school snake eats Milhouse
(As a lawyer this one comes in handy) - Worst episode…ever. (Did I miss it or has no one said this one???)
- Thank You…come again
- Money can buy goods and services.
- He sold poisonous milk to school children
(when bashing someone who everyone else likes) - “WE LOVE YOU” in a cat and dog voice, when trying to get attention from those ignoring me.
- “You don’t have a son”
- “I hope someone got fired for that one…”
- “Let’s make litter out of these literati”
SO MANY MORE!!! I’ll bet I don’t go a day without 5 Simpson references. Great topic.