Bush Onion

The Bush Onion is a close relative of the Dirty Sanchez. Where a man takes a woman from behind and just before ejaculation, sticks his finger in the woman's ass, only to pull it out and wipe a nice little pooh-stache on the woman's upper lip. Now, the Bush Onion ramps this little puppy up a notch. The man performs the above act but holds the finger under the woman's nose until she cries. Here enters the Bush Onion.

A girl's snatch that overly reeks of onions

it’s a synonym for std’s (sexual transmitted disease).