Pinch the stewardess' butt as she passes.
When two people kiss in the in flight movie, belch real loud.
When there's any nudity, hoot really loudly for a few minutes.
Fart loudly and act shocked, looking around to see who did it.
Fiddle around with the emergency exit, then ask a fellow passenger if he has a crowbar.
Hijack the cockpit and, over the loudspeaker, announce that the first class passengers and luggage are to switch places.
Run down the aisle screaming, "He's got a bomb! He's got a bomb!".
Go into the bathroom and make rude bodily noises, then come out looking refreshed.
"Accidental" soda spill on the dork next to you.
Give someone a coin, saying "Heads, I detonate the bomb. Tails, I don't".
Go into the bathroom, drop your pants, then come out, yelling "We're out of toilet paper! Stewardess!".
Describe your sex life in great detail to the five-year-old next to you.
Lead a bible study session in the back of the plane.
Start a hot dog stand.
Steal businessman's laptop, play solitaire on it.
Remark that perhaps you shouldn't have put super glue in your underpants that morning.
Pick your nose and pat the person next to you.
Show off your Batman underwear.
Switch accents and see if anyone notices.
Sneak into the cockpit and hit the warning alarm.
Scratch your butt, then sniff your finger.
Go into the cockpit, flick on the intercom light, then loudly inquire as to why the fuel dial says "e".
Go into the cockpit, ask the pilot in an obnoxious voice "Why do they call it the COCKpit?" then snort as if it's the funniest thing in the world.
Don't use deodorant, then "accidentally" stick your armpit in someone's face.
Sneeze, using somebody's sleeve instead of your hand to cover it.
Snort when you laugh.
Tell corny jokes and laugh like it's absolutely hilarious, then expect others to do the same.
Ride carry-on luggage down the aisle, yelling "Yeee-ha!".
With a desperate look, ask the stewardess where the bathroom is, then look relieved and say "Never mind. Do you have any towels?".
Jump up and scream "AAAHHH!! I left the stove on!!".
Ask someone for their autograph, pretending that you think they're Kevin Costner or Goldie Hawn (This best then the person looks nothing like the movie star in question)
If someone has a bad toupee, whack it off.
Pretend you're flying the plane.
Get some rub-on tattoos and a leather jacket, pretend that you belong to a biker gang.
Take over the plane with a toy gun.
Yell to someone "Is it time to hijack the plane yet?" (Note: Do this when there are stewardess nearby).
To the person next to you, say "It's amazing that they didn't notice the grenade in my luggage.