Sharkin (verb) - to knowingly [flirt] with a person who has a [significant other] while the significant other is not present, in an attempt to have [sexual relations] or get the couple to break up.
> Person 1: Bro, you need to keep an eye on Jenny.
> Person 2: Why?
> Person 1: She was at that party with Tom and he was totally sharkin on her.
> Billy: hey man are we heading to that girls house?
> Chad: Yea but they both have boyfriends.
> Billy: are their boyfriends going to be there?
> Chad: nope...Fuck it...looks like we're sharkin tonight.