to tightin up or pinch ( close up ) squeese
my girl clam up then I over lube . Sooo I keep telling my honey don't clam up this time, just wrap your toes around my ears and relax....
To suddenly keep unusually quiet, often in regards to the divulging of information.
Carol clammed up about the incident at the bakery, so we never did find out whatever happened to Nate.
Like tea bagging, but when a girl does it, ie a passed out young man has a photo taken with a woman's naked vulva on his face.
OMG, he got so wasted last night and Vickie said that she was going to clam up, and she totally clammed him up. Check out the photo on Flickr!