A steriotype of men who, usually residing in the United Kingdom, frequent night clubs with low reputations. They're name decends from the strict dress code and appearance which includes a white shirt. They all look exactly the same and group in tens or hundreds.
We were on our way back from Spiders rock club and were attacked by a group of shirts, officer.
Also in a song by Brotha Lynch Hung called "Rest In Piss"
All About The 91 Siccness Sacramento Bitch!!!!!
It's EBK everyday all day to the day I die/
I'm creepin through yo set with a mini Mac 10 AR 1-5/
rugga with a 12 gauge pump in the trunk
and a black beany disguise/
That nigga that you can't see glocks and locs over my eyes/