Top definition
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.
by Diggity Monkeez April 30, 2005
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2
When a girl who seems interested suddenly decides that she will not have sex.
"Hey girl, I thought we were going to get down. Why you gotta clam up on me?!"

Dude, this chick was all over me and then she totally clammed up!
by gravytrain21 July 20, 2014
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It does not matter how you do it. It's a Fecal Mustache.

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3
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!
by Cal952qCal February 27, 2009
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The vengeful act of crapping on a lover's chest while they sleep.

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4
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....
by itichie_nocanpo August 27, 2006
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Cleveland Steamer Plush

The vengeful act of crapping on a lover's chest while they sleep.

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