Everyone can contribute something. I'll add cool suggestions to the OP as I read them. Also, no typical list items i.e. get married, go bungie jumping, etc. You'll get the idea when you read these:
These are a few that I have off of the top of my head:
-Get a pack of ferrets, put them on leashes, and walk around town with them.
-Get a huge tortoise, an ostrich, and a kangaroo and ride each through town.
-Fill a dorm room with ball pit balls.
-Start a city-wide paint ball war.
-Start a moped gang.
-Dress up as a Stormtrooper and go to a Star Trek convention.
-Grow out full facial hair and then shave all the hair on one side of my body off.
-Learn how to run across railings flawlessly, dress up as a samurai, and do so on a campus while carrying a katana.
-Get a friend to dress up as a stereotypical cartoon thief and have him walk through a public area carrying a large bag with a money symbol on it over his shoulder. Then come out dressed up as Batman, chase him around, beat him up, tie him up, and then hang him up somewhere with a note attached to his shirt that reads, "Please arrest me" Then leave, come back dressed as a policeman, and drag him away.
-Go into a videogame store, grab an empty console box, and run out with it.
You got any fun ideas?
-Eat own weight in goldfish crackers.
-Run around in public shouting "Batman and Robin was better than the Dark knight!".
-Get a taser glove and punch random pedestrians in the face.
-Tame a Lion.
-Skydive into a giant bowl of pudding.
-What about stand in an elevator (preferably a full one) turn around and say: "I bet you're wondering why I gathered you here today...."
-Get covered in glow stick stuff and go out in the night.
-Swim in a pool of money like Scrooge McDuck
-Hit a grizzly bear with an upper cut.
-Eat a dinosaur.
-Invent a portal gun.
-Navigate a plane through the grand canyon..
-Enter and win a competition of for the world's most beautiful woman if a man or most handsome man if a woman.
-Run across a pool of jello.
-Order twenty McDoubles at McDonald's, eat them as fast as I can and start crying over the wrappers during the twelve o' clock rush.
-Don't rewind a tape before returning it to the movie store.
-Build a giant robot and teach it to dance.