Take the money and run

Bank Teller #1: Does this look like "gub" or "gun"?

Bank Teller #2: Gun. See? But what does "abt" mean? 

Virgil: It's "act". A-C-T. Act natural. Please put fifty thousand dollars into this bag and act natural.

Bank Teller #1: Oh, I see. This is a holdup?

Virgil: Yes

Bank Teller #1: May I see your gun?