Britannia stewardess during duty free sales:
Pax asks for Vodka Black Label.
Stewardess gets out Vodka, puts in bag, gives to pax.
Pax asks stewardess what proof it is, stewardess says it is 100% proof. Pax looks at label and says it doesn't say what proof on the label. Stewardess asks pax for his flight ticket which she then looks at and says: "It doesn't say you're a prat on this ticket but you are one"