Person 1: Oh my god! He was texting his ex boyfriend the whole time we were dating!
Person 2: What the hell? He was really pulling a hamr on you there!
Elaborating on the first definition, I believe this came up in an attempt to find a socially acceptable and fast way for guys to talk about a female that they would like to have a real relationship, none of that one night silliness.
Opposite to wanting to "tap that ass," "hit that shit," etc.
One guy to another: "See that cute girl in the yellow dress playing frisbee? I'd like to hamrel with her."