The word yak means blowjob and it can be used as any type of word such as using the noun version as a blowjob and also a verb as to give a blowjob. It can really be used as any word though because it is mysterious. This word began to be commonly known as blowjob in California when a famous celebrity Stephen Figura used it openly.
"Did she yak you last night?" -Maddie
"Yeah, she gave me the best yak ever" -Stephen
"wow that beer belly and Neapolitan ice cream is so yak" -Hannah