1. A weed (Amaranthus albus and/or Amaranthus graecizans) that has broken away from its roots and travels along the prairy wherever the wind blows it.
2. A person (traditionally male, traditionally a cowboy) with no family or romantic ties; no permanence; and no responsibilities; who drifts through life, going wherever the wind blows him.
Ex. 1: He'll never settle down. He's too much of a tumbleweed.
The act of yanking some pubic hair out of your own pubic area and depositing the (tumbleweed) into an unsuspecting asshole's beverage. Sit back and watch him pick your pubs off his tongue.