It's the classic gay porn scene from the 1992 movie
Sex Depot, with Sean Carrera sucking JJ Wad.
See also the thread below for caps from the whole scene, and more:
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JJ Wad
And this thread has a link to the whole scene at rapidshare still, with some more caps:
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Big black cock sucking
This is now the eighth active thread relating to this clip, so clearly it never loses its appeal.