It’s just a fucking word! But sometimes it can be used to response to a friend. Or it can be a short easy to say bitch
Girl#1 hey girl wassup
Girl#2 nothing much. Wassup up with you b
The second letter of the english lexicon. Probably the only real definition on urbandictionary.com.
for some reason urbandictionary.com won't let me not define the word but IT'S A LETTER" the letter b!