Another word for Cocaine and/or Cocaine accessories.
A Yak is a bison/buffalo, which a white variety is found in the Himalayas.
Coke users are known to be "bull-headed," hence the Yak-
Head word, won't ever shut the fuck up (yaking it up all night talking on the phone.)
The only difference between a Crack-
Head and a Yak-
Head is a a Yak-
Head is powder Coke User, while we all know what a "Crack-Head" is.
"Crack-back"
"Crack-Yak"
If you ever hear someone asking for Yak, that guy is a Triple OG so proceed with caution.