Its the raunchier version of the fake moustache. A phenomenon sparked by Members of the
republic of Movember who fail to grow a substantial
mo. The fake moustache used often resembles a Merkin rather than a real
mo.
Mokin can also refer to a moustache that is poorly maintained or is one of sparse or irregular growth and resembles pubic hair rather than facial hair.
Hey mate, that
mo looks like it belongs between your
legs... is it a
merkin? Ha, of course not, it's a Mokin!