the plot of big momma's house is martin lawrence in a fat suit and a dress . 
that's not just the high-concept premise ; it's the fully-realized , all-encompassing plot . 
such an emphasis is not unheard-of in the world of hollywood summer entertainment . 
one need merely look back to last summer , when the plot of big daddy was adam sandler being an incompetent surrogate parent . 
the trap inherent in such an approach is that the high-concept plot idea better be pretty well-realized , or rest on the shoulders of an extremely talented performer , because you can bet there will be nothing else worth a second of your time -- not a developed character , not a provocative theme , not a witty twist . 
you will get 90-plus minutes of martin lawrence in a fat suit and a dress -- nothing more , nothing less . 
those who find martin lawrence more than an occasionally amusing screen presence may have a shot at enjoying the one-note dud that is big momma's house . 
others will simply stare , mouth agape , at its sheer unapologetic laziness . 
lawrence plays fbi agent malcolm turner , an undercover expert on a stakeout assignment with his partner john ( paul giamatti ) . 
dangerous convicted bank robber and murderer lester vesco ( terrence howard ) has escaped from prison , and the feds think he's headed for his former girlfriend and presumed-but-never-proved accomplice sherry ( nia long ) . 
sherry , however , has fled with her son trent ( jascha washington ) , possibly to visit her grandmother hattie mae ( ella mitchell ) , better known as big momma . 
indeed , sherry appears to be on her way , but big momma is headed out of town without knowing sherry is coming . 
that leaves master of disguise malcolm to go under very heavy cover as big momma and find out what sherry knows . 
big momma's house's bloodlines are certainly traceable to mrs . 
doubtfire -- director raja gosnell edited that film , and the makeup effects were similarly created by greg cannom -- but there's just as strong a whiff of tootsie in the main character's attempt to use his alternate identity to get closer to a woman . 
unfortunately , big momma's house makes a ridiculous decision neither of those other films made : instead of having the protagonist pose as a completely manufactured character unfamiliar to anyone elses , it places malcolm in the position of playing a friend and family member to several other characters . 
suspension of disbelief in big momma's house requires you to believe every other person in the film is blind and/or stupid , since no one notices that one big momma looks or sounds absolutely nothing like the other . 
of course , laughs trumps logic every time , and big momma's house probably still would have worked in spite of its utter disdain for common sense if it had just managed to be funny . 
and it misses its best possible opportunity for some great farce by ignoring the simple fact that the real big momma is set up as a foul-tempered beast , while malcolm has to be nurturing in order to get the information he wants out of sherry . 
unfortunately , no one involved appears to have the faintest idea how to deal with the comic gold mine involved in one real person pretending to be another , very different real person , so they fall back on an endless parade of sight gags : malcolm reacting violently to big momma's explosive diarrhea attack ; malcolm-as-momma schooling a pair of cocky teens in basketball ; malcolm trying to avoid detection as various prostheses give way at inopportune moments ; malcolm delivering a baby because big momma is the town midwife ( one of the few sequences that works ) . 
martin lawrence can be likeable enough at times , but there's no reason to care a whit about his budding romance with sherry because malcolm is never an independently significant character . 
he's just big momma without the makeup on . 
i won't waste time commenting on how ineptly the set-up of the escaped convict is employed , since it was clearly a waste of time to the film-makers . 
there are a few token scenes of lester looming as a threatening figure , but he's ultimately a distraction in a film that's really about its central visual incongruity ( and the accompanying lascivious glances at nia long's posterior ) . 
i'm never prepared to underestimate how appealing that idea may be to other people -- several million of them apparently found adam sandler as an incompetent surrogate parent appealing -- but i know that when a film-maker tries to throw a concept at me and pretend that it's an entire film , i duck out of the way . 
the gross implausibility of big momma's house might have been tolerable if it was seasoned with more big , cleverly-constructed laughs . 
its lack of big laughs might have been tolerable if its characters were at all relevant . 
big momma's house is ridiculous _and_ not funny . 
it's just a sad exercise in the jaded presumption that any scene should be considered wacky and hilarious if it involves martin lawrence in a fat suit and a dress .