experience flatulence (formal words)
All verbs. Words in purple can also be used as nouns.

children's terms (kids only!): make a stink, cut the cheese (sometimes adults use this)
example: At the school pageant, Mark cut the cheese so many times that Simon wished he had taken the front of their cow costume.

polite terms (euphemisms): pass gas
example: Polite people never pass gas. They just clear their throats a lot.

okay terms: break wind, toot, shoot the breeze (double meaning: also means have a casual conversation)
example: Beans, beans, the musical fruit, the more you eat, the more you toot! (traditional rhyme)

impolite terms: fart, blow a fart, cut one, backfire, let one rip, SBD (silent but deadly)
example: It was an embarrassing day at the emergency room after curious Sandy let one rip onto a lighted match.

urinate (formal word)
Verbs unless otherwise noted. Words in purple can also be used as nouns.

children's terms (kids only!): pee, go pee, make pee pee, make water, make wee wee, go number 1, go potty, go
example: All I want for Christmas is a doll that can go pee pee!

polite terms (euphemisms): go to the bathroom, go to the restroom, powder my nose (women), visit the little girls/little boys room, relieve myself
example: While Janet was powdering her nose on the camping trip, she was eaten by a bear.

okay terms: nature calls!(exclamation), pee (some people think that's impolite), tinkle, piddle, spend a penny, make a pit stop
example: I'd love to hear the details of your prostate exam, but nature calls!

impolite terms: Take a leak (men), piss, take a whizz (men), bleed the lizard (men), drain the snake (men)
example: To demonstrate his love, Frank spelled out the name of his girlfriend in the snow while taking a whizz.

defecate (formal word)
All verbs. Words in purple can also be used as nouns.

children's terms (kids only!): poop, go poo poo, make poo poo, go number 2, go potty, go, make caca, make doo-doo, make a B.M. (bowel movement)
example: Mommy, kitty went poo poo on the carpet again!

polite terms (euphemisms): go to the bathroom, go to the restroom, powder my nose (women), visit the little girls/little boys room
example: If she wasn't really drunk at the party, why was she powdering her nose in the hall closet?

okay terms: do my business
example: Steve was so stressed over the outcome of the Super Bowl that he was unable to do his business for a week, creating a football of another sort entirely.

impolite terms: shit, crap (crap is more polite than shit), pinch a loaf, dump, take a dump, dump a load, drop a turd, make a deposit
example: After being fired, Jack showed his feelings by taking a dump in the top drawer of his manager's desk.