Jumper, bystander
Setting: City Street
(A person is jumping on up and down, yelling 49! 49! 49! The second person comes by and notices this; he asks what he's doing.)
Victim: What are you doing?
Jumper: I'm jumping up and down on this manhole yelling 49! 49! 49! It's really fun! Wanna try?
Victim: Sure!
(He takes the jumper's place and yells 49! 49! 49! All of a sudden, the jumper pulls the manhole cover out from under the victim, who falls into the sewer.)
Jumper: 50! 50! 50!