What on earth is all the hullabaloo over gums?

[Brother Buzz]

9. Does this look like "gub" or "gun"?

Teller: What does this say?
Virgil: Uh, can’t you read that?
Teller: I can’t read this. What is this? "Abt natural"?
Virgil: No it just reads, “Please put $50 thousand into this bag. Act natural."
Virgil: (pointing to the note) "I, uh, am pointing a gun at you."
Teller: That looks like "gub", it doesn’t look like "gun". No, it’s "gub". That’s a B.
Virgil: No you see, it’s an N … G-U-N.
Teller: George, would you step over here a moment please.
Teller: What does this say?
George: "Please put $50 thousand into this bag and … abt" — What’s "abt"?
Teller: "Act". Does this look like "gub" or "gun"?
George: "Gun". But what’s "abt" mean?
Teller: It’s "act" … A- C-T, act. Please put $50 thousand into this bag. Act natural.
George: Oh, I see, this is a hold up.
Virgil: Yes.