Top definition
Short for King of Substance Abuse, That one friend who gets completely shitfaced and abuses multiple drugs almost everyday.

Note: There is a "B" instead of an "A" because the "A" is very quiet in abuse.
BRO 1: dude, did you hear about what john did last night at the party?

BRO 2: yeah well he is the KOSB so I can't say I'm surprised...
by therealKOSB October 09, 2011
Mug icon

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug