MSB

short for 'Massive Sperm Buildup' - usually occours in young male adults under 25 as a result of no sexual activity for more than a week or 2

Derek had not masturbated for about 3 weeks and was suffering from a severe case of MSB, but after watching 5 minutes of crazy cumshots #4 he had a massive sperm bomb and had to use his blue bandanna to clean up!

by Cam Bomb February 19, 2012

MSB

A person with an extremely huge mullet who constantly wears sweatpants and snowboots in public places.

Big Dan is the biggest "MSB" in the whole world.

by One Eyed Jack March 8, 2004

msb

middle school bitch. one that wears excessive amounts of abercrombie apparel, attains a facebook around age 12, and always seems to have a new series of naked pictures out. Identifying an msb: prefers to straighten her hair, owns some sort of coach bag, says things like "loves it" and AlTeRnAtEs CaPiTaLiZiNg LeTtErS wHeN sHe tYpEs. like so (the written msb language also often includes numerous asterisks, hearts, and exclamation points.) <33 :)

"That msb sent me pics last night, so I sent 'em to everyone I know."

by caitymoomattyshu December 4, 2008

msb

abbreviation for “my sweet boy”

i love you so much msb!!

by Macho cowboy April 11, 2019

msb

mad swan BLOODS da real gangstas from da eastside....¢k all day muthafu¢Ka

give it up for this swan eastside m-s-b G- Batman from the the BLOODS and ¢Krips song G'z and lo¢'s

by b-dog fo eva August 10, 2004

msb

A Acronym derived on the MMORPG "Runescape" First used by a player known as Staple,or "Nibo." It means (M)ad (S)ad (B)ad as a flame toward raging players that are considered "Bad" at the game.

l0l why you so msb bro?!

by StapleNibo April 6, 2011

msb

Mushroom Shaped Bruise

A bruise left after being brutally slapped with a penis.

Sir, u are worthy of an msb or 2.

by Aurarier November 29, 2004