A friend of mine had this little gem: "When life gives me lemons, I make beef stew." I love it; it's a great attitude to have towards existence.
As for me? I usually just quote other stuff, but I'll occasionally have my moments.
"I'm not Catholic, but... *crosses self* every little bit helps, I guess."
"I'm white, male, Christian, right-leaning, and will soon be both an Army officer and college educated. It's clear that, in about twenty years, I will be 'The Man'. Stick it to me, I dare you."
And an old standby, used by a lot of people, but one that I am particularly fond of: "Ugh. This is gonna suck."