I love this scene from the Break-up and it's a perfect illustration of the two shirt guys:
Gary Grobowski: You want to go get a drink? No.
Brooke Meyers: I'm with somebody, sorry.
Gary Grobowski: Who? The guy with the tucked-in shirt and the visor? What, is that like a brother? The guy was not your brother, then.
Brooke Meyers: He's not my brother.
Gary Grobowski: Who is this guy? Who's this... I'm getting mad now. I'm jealous. Who is this guy?
Brooke Meyers: Who are you?
Gary Grobowski: I don't know. I'm kidding with you. Who's the guy with the tucked-in stuff? Is that a boyfriend?
Brooke Meyers: It's...I'm going.
Gary Grobowski: Do you think you'll marry him? Cause I know you've thought about it. The first time you laid eyes on him, you probably thought, I wonder if I could marry this guy in plaid shorts who tucks his shirt in. Then when you kissed him, you said, I can't believe it. I had a lot to drink tonight. I'm kissing the tucked-in guy. My point is, if you're not gonna marry him...and if it's not forever, then you really don't have anything to lose in taking me up on my offer.
Brooke Meyers: Well, I'm gonna go.
Gary Grobowski: Okay. Me, too. To where? On an ice-breaking first date?