What does "mental" mean in this sentence?
He said no, he didn't remember that at all, and she signed deeply to let him know she thought he did, pointing, then, to a house on the corner done all in blue lights, strings of blue lights up and down the whole front of it, turning her head to keep looking as the car moved past.
He said, "I am mental, Janie."
"Very mental," she agreed. "You have the ticket?"
"Funny to have tickets in order to get into a church"
Could anyone tell me what "mental" means in the conversation?