Throughout the movie he makes reference to the three brains we have - the reptile brain, the mammal brain and the human brain. He calls them crocodile, horse and human respectively. He seems to use his reptile brain since he is a killer who is cold and calculating - he gets women to love him so he can then drink their blood. He also cries in the movie which were like "crocodile tears" - false tears to indicate an emotional response that is actually nonexistent.
Well, at least, this is what I got out of it in relation to the title!
Hope it helps:)
"Tragedy is when I cut my finger. Comedy is when you fall in an open sewer and die" Mel Brooks