You want a Christmas card? Here's your Christmas card!
Why?... because it's funny as hell.
No soup for you!
Why?... because it's much more colorful than just saying 'no' all the time.
I also try to use the words 'Gipple' and 'Mulva' as much as possible... though it's often hard to slip those into a conversation.
P.S. hats off to the first guy with enough cajones to admit that 'Shrinkage' is the one he uses most often (and we know you're not talking about laundry).
When someone is publicly humiliated: "I was in the pool!"
Any denial: (variation of) "No soup for you!"
When busting out the chips and salsa: "People like to say, 'SALSAAAA'"
"Sven-jolly"
"Some charlatan has stolen a Ziggy and passed it off as his own. And I can prove it! Quick Elaine, to the archives!" (I admit it can be difficult to work that into everyday conversation but it's fun to repeat anyway. )
"treating [one's] body like it was an amusement park."
When someone fails to live up to expectations: "Why can't you be more like Lloyd Braun!"
When trying (unsuccessfully) to relax: "Serenity now. SERENITY NOW!!"
Of course the classic "Not that there's anything wrong with that" I use almost daily and a buddy of mine almost always chimes in with "My father's gay".