When a man and a woman engage in cunnilingus in a particular manner.
The man must be big burley and have a large beard. During said oral sex, the man must "motorboat" the woman's vaginal area.
Guy 1: Hey did you see Tom at the last party at Jay's spot?
Guy 2: No why?
Guy 1: Oh dude Tom grew this huge beard and totally gave this drunk hottie a downtowner!
Guy 2: That rocks bro!
n. Person who grows up in a dense urban neighborhood ("downtown") as opposed to the growth-friendly suburbs.
Generally these people are socially awkward, unusually tense, and don't have close personal friends, but rather a large group of acquaintances they call "friends". They know everyone and no one at the same time.
Often flaky.
"I can't handle Irina at these parties, she's such a downtownie."
"She doesn't understand going to play soccer, she's a downtownie."
"There is no way Tom's going to make it out to your jam, he's a downtownie."