In the second act of “Mean Girls” on Broadway, something oddly familiar happens. Damian, the “almost too gay to function” drama nerd, sings a song called “Stop,” advising other high school students against impulsive choices like trolling and tattoos. Then he sells his message with a big tap number, the only one in the show.

What’s familiar about this has nothing to do with the 2004 movie from which the musical is adapted. It is oddly familiar only if you notice its similarity to numbers in otherwise dissimilar shows. How dissimilar? How about “SpongeBob SquarePants: The Broadway Musical,” based on the popular cartoon, and “Escape to Margaritaville,” the laid-back musical made out of Jimmy Buffett songs?

All these shows, believe it or not, have tap numbers that resemble one another, above all in tone. The fact, for example, that Damian is tapping and inspiring others to tap is treated as at once absurd and worthy of an ovation. “What could be more ridiculous?” the number seems to say, while at the same time insisting, “Isn’t it fabulous?!” This is “a big tap number,” in quotation marks, and a symptom of what tap has come to mean on Broadway.

At first, the trend might seem to be just another case of everybody imitating the popular kid. As Ben Brantley noted in his review of “Mean Girls” in The New York Times, Casey Nicholaw, who choreographed and directed the show, borrows in “Stop” from the 2011 megahit “The Book of Mormon.” So, it seems, do the choreographers of “SpongeBob” (Christopher Gattelli) and “Margaritaville” (Kelly Devine).