A practical joke is a mischievous trick or joke played on someone, typically causing the victim to experience embarrassment, perplexity, confusion, or discomfort.
One common practical joke is called a wild-goose chase, which involves someone sending someone on a task that is often impossible to achieve. Such practical jokes are often done while hunting. An experienced hunter might send a less experienced hunter on a hunt after and impossible target, such as a goose or duck.
When Superman goes to the City Line Traffic Circle in Gotham City to stop what he thought was an Alien Invasion, he realized once he saw that the flying saucer was actually made of a type of plastic called FRERP, he thought that it must have been someone's idea of a practical joke. In actuality, it was a plot devised by King Plasto to keep Superman busy while he continues his master plan.
Wendy had an egg that she claimed was a FRERP egg and said that the letters on the egg were "R.E." Marvin then wanted to see the egg to determine what might be inside, so she tossed the egg over to him, but it splatted all over his head. He knew then he had been the victim of a practical joke, and he said because the handwriting looked familiar, just like hers, and because of the "twinkle in [her] eye and the egg on [his] face."