A boy asks his father to explain the differences among irritation, aggravation, and frustration.

Dad picks up the phone and dials a number at random. When the phone is answered he asks,
"Can I speak to Roger, please?"
"No! There's no one called Roger here." The person hangs up.
"That's irritation," says Dad.

He picks up the phone again, dials the same number and asks for Roger a second time.
"No, there's no one here called Roger. Go away. Don't call again."
"That's aggravation," says Dad.

"Then what's 'frustration'?" asks his son.
The father picks up the phone and dials a third time:
"Hello, this is Roger. Have I received any phone calls?"