"Musk" originates from "muskrat". It was originally used to describe overly aggressive use of the mouth in sexual acts, such as biting.
Musk has now expanded to mean going hard on anyone or anything. Much like "going HAM", musk is a state of mind. To musk is to fully rip into the situation and go 110%.
One can either go musk, musk on, or simply musk, depending on context.
Musk can also be interchanged with virtually any lyric in popular music to create a musk anthem.
"Yo bro, I haven't been able to drink for two weeks cause of my antibiotics. We gotta musk the shit out of tonight to make up for lost time."
"If you're going to pay $1500 to go on Spring break, you better be musking THE hardest"
"Last night I totally went musk on John. I can't remember the last time we had such crazy sex"
"Musk so hard muskafuckas wanna musk me"