How do you make an egg roll?

The joke takes advantage of the literal interpretation of the words “egg” and “roll.” In this context, “roll” is a verb meaning to move something by turning it over and over on a surface. An “egg” is, of course, an oval-shaped object that can indeed roll if pushed.

The humor arises from the unexpected twist. Instead of providing a recipe for making an egg roll, the answer “Push it” refers to the literal action of making an egg “roll” across a surface. The surprise and incongruity between the two meanings of “egg roll” are what make the joke amusing.