Shaggy from Scooby Doo went to Megan and Conner’s high school.
You may think it’s just a costume but remember Scooby Doo is set in the same universe as YJ.
This is a scene from Scooby Doo Wrestlemania it features four girls resembling Megan, Zatanna, Artemis and Cassie in a watching the wrestling match at the end of the movie.
There is a 5-year gap between season 1 and 2 and Shaggy is canonically a college student and Wally and Artemis are both in college in season 2 which means that this is very plausible.
Superboy 