There's no point explaining the flimsy buddy-com clichés that force an FBI agent (Martin Lawrence) and his son (Brandon Jackson) to go undercover at an all-girls art school in Big Mommas: Like Father, Like Son, a follow-up to 2000's Big Momma's House and 2006's Big Momma's House 2. It's all an openly lame excuse for Lawrence to hop back into the eye-assaulting muumuus of his alter ego Big Momma, a wheezing, overripe hybrid of a Southern dumb-belle and a Julia Child drag impersonator. The trouble is, once the movie drops its cop-drama trappings, it doesn't do any better as a comedy. Lawrence's gender-bending jokes are played out, and his slapstick is wooden and slow. It's understandable: Clowning around underneath that fat suit must be exhausting. Almost as much as watching it.