Originally american slang meaning to fight someone or being aggressive towards someone.
Used commonly in America and in England. If you say 'Do you want beef?' to someone you will usually end up fighting or maybe even passing away
Northside Rudeboy: Man you cant spit
Southside Battyman: WHAT?? U WANT BEEF BLUD... GONNA GET SHANKED
LYK A BIATCH YOU FUKIN PRICK
Northside Rudeboy: Shut the fuck up you dick... *pulls out a gat*
Southside Battyman: No beef, man, no beef, allow it bruvs.. ALLOW IT!!
*CAP!! CAP!! CAPCAP!!!*
Southside Battyman: ...fuck... biatch.. southside for lyf!.. ya hear fuker!!
*Rudeboy aims at battyman's head*
err.... i mean northside for lyf