Thread: What is...

Mocha, mocho, in Mexico, is slang for people that is extremelly religious and yes, mochilla is the same, with a pint of afection but still means criticism. It is used mostly in reference to people that is very religious in the external ways and means no criticism of your inner convictions. It is certainly a crticism of outer appearances. Religious intolerancies are also worth the label of Mocho, mocherías. The origin of the term is not clear to me. Mocho, mochar, is to cut an extemity of something. Un árbol mocho would be a tree that has been severily cut. Also means the opposite of "cabal" (whole).
There is a current slang (totally different from previous sense and has nothing to do with your question), very used in Mexico: móchate, se mochó, me mocho. The meaning is to share something, because you cut, by half or not, what you have and then share it. You are smoking a cigarrette and a friend comes and says "mochate", as a way of asking a cigarrete from you.