Shenanigans, Pt 1

Pulling pranks on people is generally juvenile and gross. If stag parties are any indication, most people's talent for practical jokes does not extend beyond combining hapless victims with various bodily fluids (or worse, bodily solids).
To show how the pros do their stuff, refer to the enthusiastic lot over at Improv Everywhere, who use practical jokes to make everyone's day a little more surreal. Check out Best Gig Ever, for example, where the gang cheer on an unsuspecting New York band performing in a bad Manhattan venue in the worst slot of the week. They also celebrate a random stranger's supposed birthday, and the best part of the prank is the guy's response.
You might consider these pranks mean until you realize that they're actually pleasant for the 'victim'. It is a well-documented fact in psychology that people who mind about this kind of thing generally mind the unusualness rather than the unpleasantness of the experience. Like the manager at the Virgin Megastore who calls the cops because people in his shop start a synchronized dance routine.

Megastore guy: They were all just standing there.

Cop: What were they doing?

Megastore guy: Just standing, and then they all danced.

Cop: Did they say anything?

Megastore guy: No.

--Pause--

Cop: Why are we here?

Upsetting these kinds of people should be everyone's ambition.