A gentleman and his friend come up to the reference desk:
Guy: I would like to buy a Spanish-German dictionary.
Me: Well, we don't sell any books here. You just borrow them, and then you bring them back.
Guy: (looking confused) You don't sell them?
Me: No, just lend.
Guy: How long can you borrow them for?
Me: Three weeks.
Guy: (to friend) Huh! That's not bad! (to me) And how much does it cost?
Me: Nothing; it's free.
Guy: (he and friend are completely gobsmacked by this idea) FREE?!?!
Guy and Friend: WOW.
And just to make us even more awesome, we actually had a Spanish-German dictionary.