"Yeah." Bart said, sheepishly and shrugged, "Yeah I just..." Bart paused for a minute, rubbing the back of his head and looking way, "Hey if I tell you something, do you promise not to freak out?"
Bart had already told him that he was superhero and had superpowers-- but in his own mind, his other secret was probably more freak out worthy; and it wasn't even the big secret.