Admit it, you abused your kid brother/sister/cousins. You probably told them stories about "the bogeyman" or put them up to do obnoxious things. Like sending them to Sunday school to ask "Can God make a rock so big that he can't pick it up?"
Greenhorns and apprentices get a lot of this too. They might be sent on missions to pick up some prop wash or a left-handed crescent wrench. After hours they might be taken on a snipe hunt.
A few years ago I found myself exposed to horses quite a bit and I learned a lot. I thought someone was pulling my leg when they told me that horses couldn't vomit and were extremely vulnerable to digestive problems. After seeing a couple of them hauled away on endloaders I became a believer.
Then someone told me you could make a seagull explode by feeding it Alka-Seltzer. Hmm - anybody who has parked near the ocean can see the appeal of this. After the horse experience, well...no, this had to be bogus. Here is confirmation from the ultimate source of everything worth knowing, Cecil Adams of The Straight Dope.
Yo, Hawspipe - any comments on the seagulls?
UPDATE - I guess horses can vomit after all. Yeah, I know - thank you for sharing.