A high school principal has decreed that Captain Underpants has no place in an institution of learning.

Three 17-year-old girls were told to leave Long Beach High School on Wednesday after they showed up on Superhero Day costumed as the subject of the best-selling children's books.

"I didn't know which superhero it was, not that it mattered," said Principal Nicholas Restivo.

The girls depicted this superhero — who has battled, among other things, talking toilets and the infamous Professor Poopypants — by wearing beige leotards and nude stockings under white briefs and red capes.

"Yes, I know they weren't naked," Restivo said. "But the appearance was that they were naked."

"They're not see-through or anything," said one of the girls, Chelsea Horowitz, an honor student and softball player. "All the teachers thought it was cute."

But Restivo made his decree: There would be no visible underpants in his hallways.

And thus, Horowitz and fellow seniors Ashley Imhof and Eliana Levin went home to change back into their mortal attire.