The Jail scene (spoilers)
Was the funniest and best part of this movie. Starting with the dialogue ("What the f*ck did you do to get in here, forget to separate the recycling?") to the transformation (both Madison and the faces of the inmates going from mean to scared shitless) to her walking backwards the whole time and ripping the women apart. Add to that the interspersed scenes of her step mom and sister getting the shock of their lives after seeing Gabriel for the first time.
I was literally LMAO!
A lot of people in IMDb are complaining about how over the top and absurd this flick is, but it's actually one of its strength IMO. I would say it's a bit like The Cabin in the Woods - not just horror, but also has lots of comedy, gore, absurdity and is brave enough to revel in its campiness to the end rather than try to tone it down or take itself too seriously.
Edit*: Also wanted to add that the music/score was great and reminded me of the Resident Evil movie series