In line at the grocery store. Big sign in my lane says “EXPRESS LANE. TEN ITEMS OR LESS.”
Cashier: Sir, just so you know for next time, this lane is for ten items or less.
(I’m behind Sir, attempting to purchase a single item)
Sir (in line with eight year old girl): Hmph. Ten items. Fuck ten items.
Cashier: I mean, just so you know for next time.
Sir (looking rather intoxicated on closer inspection): I don’t give a…ten items…well I don’t give a…
Cashier: You know, so it’s fair for the person behind you who has only one item.
Me: Blushes, shrugs.
Sir: Whaddayou give a shit. Ten items. Fuck you. Fine then. Fuck.
(cashier rings up 20+ items and Sir swipes card)
Cashier: Um. Could you try your card one more time, sir? For some reason it didn’t go through.
Sir: Fuck. (Swipes again, swoons a little and jabs at the numbers on the punch pad).
Cashier: Thank you sir.
Sir: Mumble, mumble. Fuck. Mumble mumble (walks away with purchases and young girl).
Cashier: (Exhausted look) Sorry ma’am.
Me: I just feel so sorry for that little girl. And you.
Cashier: Sigh. Nod.
Three Taboos 
That sounds pleasant. I could probably take a stab at her vocabulary words.