For three days straight, my dear son has been pretending to be Velma from Scooby-Doo. I am Daphne, and Jeff is Fred. Yesterday when I woke him up, saying "Time to get up, Vinny!" the first words out of his mouth were "You mean Velma."
There is a positive side to it, though. We've been able to convince him that in order to solve mysteries, he needs to have a good night's sleep and eat a good breakfast.