I get this, my Ob said it is headbutting (or some other part) of the cervix. Not a very fun feeling, sends the electric shock thing right through your body, I've yelped a few times because it definitely catches you off guard! I'm 32w and bub has been head down for a while, DD was the same and had the same fun feelings... my bubs seem to prepare early (DD arrived at 38w though on the dot).