To vomit, typically after heavy drinking. A portmanteau of the colloquial vomiting description "to yak" and the popular professional fishing tournament "Bassmaster Classic."
John: Dude, Kevin had way too much tonight...I think he's having a Yakmaster Classic in the bathroom right now.
Kevin: Just give me a couple minutes, I'll be fine! (pukes)
A person whose mouth is so fine-tuned, they're given the title "yakmaster."
Dude: Susie wouldn't shut up last night at the party, her mouth 90 miles an hour until someone said, "would the yakmaster please shut the fuck up?"