FAQ for
Big Momma's House (2000) More at IMDbPro »

What I know is the scene shows that during that night Malcom who is dressed up as big momma took the big momma mask off so he could sleep better without his face sweating under the mask. That is why his musdache is showing. Then the next scene in the morning it shows he has put the Big Momma Mask back on probably after Sherry went to sleep so that she would not notice that who she thought was Big Momma laying next to her was a man.

In order to obtain a BBFC-12 rating, four scenes, all involving fight sequences, had to be cut, e.g. head-buts or kicks. This leads to a difference of 8 seconds. A detailed comparison between both versions with pictures can be found here.