Top Definition
1. The biological term used for the species renowned for its ability to squeeze objects of all shapes and sizes into and out of its anal passage.

2. One who is extremenly anal-retentive.

3. The tightest orifice on the body.

4. The most potent and deadly of all the assholes.
Wow! I thought I could shot a ping-pong ball far until I saw sphinctosaurus rex.

I wish he would lighten up -- he is such a sphinctosaurus rex!

I tried to slip it in to his sphinctosaurus rex, but there was not enought santorum to make it happen.
by Stanky April 18, 2006

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