Everybody loves a good fair ground ride and so why not give them something to panic about more than a few bloody pranks?
'The water, it burns!!' : Two friends or one person will go on a water ride, preferably in a carriage with other people they don't know or if they go alone they can scream this part at the people watching. While the ride takes off, suddenly the friend or the person alone will start panicking and shouting to the people watching or the people sharing the boat/cart with them that they can't swim and that you need to get off. Perhaps a little panicked rocking of the boat/cart will add to the role and then when water splashes in the persons face he or she can begin screaming IT BURNS, OH MY GOD IT BURNS!!! and start crying.
'Dude, where's my arms?' : Two people get on a roller coaster, one of them will have fake rubber or foam arms sticking out of their jacket in place of their real arms which will be inside of the jacket. Ideally, the two friends should be sat in the middle of the roller coaster cart. As the roller coaster sets off, the person with the fake arms will hold them in the air or let the air raise them and then make it look like they have been ripped off going under one of the roller coaster tracks. The other friend will have fake blood or ketchup on him or her so that they can spray it all over their friend to add to the grossness and people may be sprayed with the blood in the back of the carriages.
'Exploding Candy' : Person walks up to one of the candy floss stalls and orders some. While eating, the person will already have a blood bag in their mouth which they will bite on as they eat the candy floss and will make out that the candy floss has sliced up their mouth. The person will panic and lie on the floor gurgling or something!
'Next stop, sir?' : Although this may not count towards a fair ground theme it can be done in a local fair ground hotel, and ideally by a very fit person willing to do a lot of stairs or a number of jackass's on each floor to help with the prank. Someone pretends to be on the phone while on the ground floor and while people go into the elevator they run to the second floor or alert the next jackass on the next floor that people are in the elevator and that jackass presses the button so the elevator stops at that floor. Then when the elevator stops and the people look around confused and it goes up again and then someone presses the 3rd floor button and so on and so on. Ideally this would work for people wanting the seventh floor or higher, also if the prank needed a bit more juicing up, have someone sat on a chair infront of the elevator doors each time they open and the person on the chair be in some sort of funny animal fancy dress or doing something peculiar.
'He was a cowboy, a wet cowboy!' : A bunch of the jackass guys pose as cowboys riding broom stick horses or those kiddie horses with wheels you can get and start racing around the fair re-enacting a wild west scene and shooting people with water pistols.
I couldn't find anything in the rules to say we were only limited to one idea so I figured instead of sending loads of entries, send the one with a few ideas on. Please don't penalise me, if you can't accept this entry due to there being more than one idea (although based at a single place) please let me know and i'll try and figure out one to send.
Thank you kindly for reading.