A verb used to describe someone being very attracted to someone else. When someone has a crush on someone, they would be described as "crushing on him/her"
Ben: Hey, Sean. What's up?
Sean: Oh my god, I'm totally crushing right now.
Ben: Wow, Sean, that girl Julia over there looks pretty hot.
Sean: Yeah, I think I've developed a crush on her.
Ben: So you're crushing on Julia?
Sean: I suppose you could say that. Yes, I am crushing on Julia.
Jimmy Fallon is a former cast member of the popular NBC sketch comedy show Saturday Night Live. He is often referred to negatively as he often broke character or laughed during scenes. He went on to star in such films as Taxi alongside Queen Latifa, and Fever Pitch with Drew Barrymore.
Jimmy Fallon can also be used as a verb. When someone is expressing qualities that Jimmy Fallon often does, they would be "pulling a Jimmy Fallon."
Ben: "Hey Sean, did you watch Saturday Night Live last night?"
Sean: "Yes, it was pretty good, but I was a little distracted by Jimmy Fallon's hysterical laughing."
Ben: "Yeah, at first it was kind of funny when he forgot a line and started chuckling, but now it's getting a little old."
Ben: "And then the man went over to...*laughing*"
Sean: "Alright, cut. We have to keep starting the scene over because Ben's pulling a Jimmy Fallon."
Ben: "I'm sorry, I just find myself so entertaining."