That, and “Seymour has to use the toilet! His bladder is full! Full of urine!”
I’ve disarmed a few Crusaders with the:
“won’t someone Pleeeeeese think of the children!?”
Oh, yeah!
I’ve had occasion to use two Ralph Wiggimisms:
I beat the smart kids–Used when you’re the only one who knows the answer.
I bent my Wooky.–A good answer to “What’s new” or “What’s wrong” when you don’t want to explain.
Another vote for cromulent.
I fairly regularly throw the word “embiggen” into stuff and meetings etc. It is always a bit of an icebreaker when someone gets the reference and says that “embiggens is a perfectly cromulent word”.
I can do the Barney burp too.
I love using “Stupid economic recovery”
(from when they fled to the no-longer-abandoned warehouse)
And, as a non-sequitur, possibly the most brilliant quote from the Simpsons:
“Ah, the Luftwaffe - the Washington Generals of the History Channel”
There’s always the standard Burns evil “Excellent…” while steepling your fingers.
And after seeing it last night, I’m looking forward to using the Burns line:
“Let me put up my legs and pollute my britches in delight!”
When we’re dividing responsibilites, such as you go get your stuff or whatever and “I’ll deal with those murderous trolls…ugh I mean, I’ll deal with those murderous elves”.
And any time I need a shower, Homer’s “I’m as filthy as a Frenchman!” comes in handy.
D’oh, thats trolls both times.
When the Tim Burton remake came out on DVD, the kid who sits across from me at work said ‘Paul, you know the Planet of the Apes?’
Quick as a flash - ‘The film or the planet?’ 
hah hah, yoink, who’s in the what now? are all staples, as is ‘Just because I don’t care, doesn’t mean I don’t understand’
When I worked behind a bar, it was a constant trick between me, my brother and one of the barstaff to out do each other with random obscure Simpsons quotes.
What a time to be alive
“Cheese-eating surrender monkeys” (Groundskeeper Willie’s description of the French) seems to have gained quite a bit of currency…
I’ve used [wiggum]It’s a ghost car.[/wiggum] quite a few times.
Also used, but not necessarily following the above, is:
Homer: Hold me.
Wiggum: Only if you hold me.
Yesterday, when the spaghetti stuck together: "I hate it when the noodles stick together. "
“Sticking together is what good noodles do!”
Used many times: If something is out of reach, “I wish I had my reaching broom.”
While slumped on the couch, “Ahhh, there’s nothing like a good sit.”
If something is too good to be true, “I’m the magical man, from happy land! In a gum-drop house on lollipop lane!”
And my favorite, to be used anytime: “Your flesh mother used to bring me pudding.”
My all time favorite to use is:
“Oh, (____) are just a suggestion, like pants!” (Homor expresses this sentiment while running a stopsign but it can be used nearly any time you are breaking the rules)
The Apu “Please come again” is also very popular at our house.
I also occasionally use:
Me: “No TV and no beer makes Homer something… something…”
My wife (she’s a fan too): Go crazy?
Me: Don’t mind if I do!!
One I think I need to work into a conversation but havent yet is form the same episode.
“Tell you what. If we come back and they’re all dead, I owe you a coke.”
Meh.
You heard me. M-e-h. Meh.
And you read through 95 posts of a Simpson’s threard for what? Hoping to find something other than Simpson’s quotes?
Whoosh, I believe.
When my wife tells me to do something, I reply…
“What are you gonna sick the dogs on me, or the bees, or the dogs with bees in their mouths so when they bark they shoot bees at you?”
So are The Sims. (In Sims 2, sex is called “Woohoo” as a Simpsons reference).
I’ve never found a good use for “cromulent,” but I do use “embiggen” wherever possible.
And whenever somebody’s ragging on a different city, I use one of my all-time favorite quotes: “Those kids in [insert city name] are always eating candy! They love the sweet taste!”