Mouse in the house is when your penis is too small to have sex with a girl, so for her pleasure, you tie the tail of the mouse to your small penis and have sex with her.
Dude last night I gave my girl a mouse in the house, it was rad.
Come on man, you are trying to shit house me here when I told you that I wanted a good deal; We decided not to buy the car because the guy was trying to shit house us on the deal.