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.
"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."