There is a big difference when it comes to having a prank between someone you know such as a close friend or colleague VS pulling a prank on a complete stranger.
When you know someone, you have a good idea as to what their reaction might be, and whether or not the prank will be appropriate and in good taste so the laugh can be shared by all including the person being pranked.
I find it very inapproriate to make pranks on people you don't know, especially in the public arena without their consent. It still baffles me how Radio DJ's are able to cold call random people at will during a live broadcast.
