Sam: Man, we’re not kids anymore, Dean. We’re not gonna start that crap up again.
Dean: Start what up?Dean: Oh, bring it on, Baldy.
Sam: That prank stuff—it’s stupid, and it always escalates.
Dean: Oh, what’s the matter, Sammy, you afraid you’re gonna get a little Nair in your shampoo again, huh?
Sam: All right. Just remember, you started it.
– , 1.17 Hell House
Supernatural has a great tradition of pranks both on the Show, and behind the scenes.
Pranks on the Show
In 1.17 Hellhouse, Dean pops a spoon in Sam's mouth while he sleeps in the car and snaps a photo of it - and the prank war is on! There is obviously a long history of this between the brothers - Dean refers to putting Nair in Sam's shampoo. Next up Sam messes with the Impalaso when Dean turns on the ignition, salsa music blares from the radio and the windscreen wipers start up. Dean retaliates with itching powder in Sam's underwear. Not to be outdone, Sam puts superglue on Dean's beer bottle so it sticks to his hand.
Finally Sam and Dean call a truce and turn their attentions to Ed Zeddmore and Harry Spangler , with Sam calling them posing as Hollywood producer who wants to option their website, and make a movie and RPG based on them. Dean puts a dead fish in their back seat.