BSB

When someone has transcended the relationship status of a best friend, and are now a backseat buddy.

Holy hell, I think they're BSBs for LIFE!
No Way!

by HAIM8 January 02, 2024

BSB

Means (B)itch (S)ince (B)irth

Makayla Yoo so fine

BSB fashoo

by BitchSinceBirth March 30, 2020

Bsb

Bestie since birth. Someone u have known since birth or for as long as u can remember. U have always been there for each other and always will be. Can be boy and boy, boy and girl, or girl and girl

Girl #1: ugh I miss jack, he’s my bsb, can’t believe he had to move away

Girl#2: girl I may have not known u since birth but honey I will be here for u

by Happyhour101 August 21, 2018

BSB

Back stabbing bitch

That's really messed up that you helped that girl out by telling her, her friend was talking shit about her .. and she went to say it was none of your business then talked crap about you what a BSB

by tellabitch August 13, 2017

BSB Special

To cave ones date in. Bumsex.

Michael asked lez if she wanted to receive a bsb special.

by Flying bum September 25, 2020