[Grandpa]“I’m cold…and frightened!”[/Grandpa] in any ambiguous situation.
Years ago when I was at Uni. I was sitting on the steps of the local Quickymart with my housemate and some jerk drove by and shouted “Get a job you lazy bums” to which I replied “Thank-you, come again” in my best Apu voice.
When eating, I’ve been known to throw in either “Tastes like grandma!” or “Needs more dog.”
The last one works well when someone tries to get me to try a beer I’ve never had before.
I use the following almost daily:
When confused: “Shot who in the what now?”
When completely screwed: “Help me, Jeebus!”
When I or someone makes a mistake: “Ooh, he/you/I card read good!”
“I’m not NOT (whatever)”, from Homer’s “I’m not NOT licking toads!”
If I start coughing while I’m eating, I thump my chest and tell people I’m “Just workin” the turkey through."
And probably tons more that I use so often that I completely forget that they come from the Simpsons.
I’ve used “I didn’t think it was possible, but this both sucks AND blows” a few times.
I use, “uhhhhh…nooo” sometimes.
When someone says “Ellis, I’ve got something to tell you.” I’ll ask, “Is it about pie?”
I’m looking for the opportunity to say “You butter that bacon, boy!” (“But dad, my heart hurts.”
“Huh. You’re right, son, this does taste like grandma.” 
Another one: “I don’t know” said in the special Homer inflection. (From when he posed as Mr. Burns to get his mail and the clerk asked him what his first name was.)
This thread could go for miles…
Whenever someone deny’s me beer for some reason, I always say:
“Bouv no function beer well without.”
I also use yoink all the time.
“To alcohol: the cause of, and the solution to, all of life’s problems!”
Whenever someone says, “I knew…” I say, “Then why didn’t you tell the rest of us? Why’d you keep it to yourself?”
I don’t remember which episode it’s from, but I’ve always found Homer’s “You’ll have to speak up. I’m wearing a towel.” comes in useful in a variety of telephone conversations.
That’s from the “I Didn’t Do It” episode when Bart goes missing at the box factory and you first see Marge running to answer the phone from the shower wearing only a towel, but she’s too late; then you see Homer at work running to get the phone in just a towel, and that’s when he says that hilarious line. I love using that one too.
Be careful what you say, though. One time I said this to someone who claims to be a big Simpsons fan. Said person misunderstood the statement and started a newsletter. No foolin’. Here we are two years later and it’s still going.
A couple of times when my wife has turned the TV on to something I didn’t want to watch, I would give her a nasty look and say, “If you need me, I’ll be in my room” with the Lisa inflection.
and if I find food enjoyable… “Mmm, that’s good squishy”
Funny. I use that same quote…only not about food!
Yes, yes…I know. Make all the appropriate jokes.
What kind of a catch phrase is that?
Whenever someone cites a statistic I counter with Homer’s “Ahh, people can come up with statistics to prove anything, Kent. fourteen percent of all people know that.”
When someone brags about their or someone else’s accomplishments I employ “If he’s so smart, how come he’s dead?”
And this following, venerable quote has been used on countless occasions for countless reasons.
Not to mention the nearly obligatory “If I’m not back in [X minutes], avenge my death.”
I have misplaced my pants.
The other day I spilled a drink up at my local pub.
After I did so I said "Oh, man… This is everbodies fault except mine…"
(quoting Homer)
Everbody at the bar got a good laugh out of it. And the best thing is I don’t think they know I stole it off of the Simpsons. Which leads to the ethical question: Am I obligated to tell them?
Also my boss is always telling me TRY to get this done today. To which I always repond with: " I don’t know boss, trying sounds like the fist step towards failure…"
Boss thought it was funny the first time. Not so much so anymore…(tee hee)