A big ugly woman who is an easy fuck. So named because of the similarity to the trash barges that go up and down the river Thames in London which everyone dumps their mess into.
Dude 1: "That girl in Accounts, the fat one, everyone in the department has fucked her!"
Dude 2: "Yeah - a real Thames barge."
Dude 2: "Yeah - a real Thames barge."
by Wizards Sleeve September 3, 2006