When a man is wearing pants that are too tight for him, and he positions the seam of his pants in the middle of his junk
, or in between his testicles. The effect this has is that the balls look like two teeth with a string of floss in between them.
The opposite of lumping
From the verb "to floss".
I hate it when all of my pants are dirty and I end up flossing with an old small pair of jeans.