A Sidey
A Sidey is a guy or girl who does stupid stunts just because his friends told him to, and he ends up falling flat on his face like a total loser.
He jumped off the roof because his friends said to, and he landed like a sack of potatoes.
She did a backflip and landed on her head like a donkey.
He was a Sidey and fell off the wall like he was drunk.