Why are the children trying to give Boo Radley a note?

when the kids try this, Scout falls, making a noise so that Mr.Radley gets out of his house and shoots a shotgun in the air. This scares the kids away and Jem gets stuck in the fence between the schoolyard and the radley home. he thinks he is going to die, so he rips his pants off and runs away in his boxers. when they get home, the entire town has woken up because of Radley, and Radley thinks there was a "negro" in his yard. when Atticus asks Jem if that was his doing, dill abruptly lies and says the kids playes "strip Poker" explaining why Jems trousers were absent. the adults believe Dill and later on in the night Jem needs to go get his pants once everything had settled down. when it is late, he runs to the fence, gets the pants, runs home and presents them to an agitated Scout like a prize worthy of honor.