Best definition
What have you been doing?
Instant messaging speak. Optionally with a question mark.

<Chris> wbd?

<Tim> Not much, you?
wbd: define #2
Stands for Wicked Bitch Down South. Used as a noun. Meaning the girl is PMSing or has her period and is pissed for no reason at all. This does happen sometimes and girls know it and can’t explain it later other than blaming pms.

And yes it does get annoying to girls too.
Girl: OMFG! i HATE you! Leave me alone you asshole!

Guy1: WTF did i DO??!?!?!

Girl: Just LEAVE me ALONE! You have problems and your pissing me off!


Guy2: Dude what did you do?

Guy1: I have NO idea

Guy2: Sounds like the WBDS if you know what i mean
wbd: define #3
Acronym that stands for Water Bottle Dick. When a male has a penis that is the approximate thickness of a water bottle. This is not about the height of said water bottle. Similar to a chode.
I thought he was hot until I saw his wbd, it would have split me in half.