Between strangers, "please" is a word that makes your requests more polite. But when you use it with someone you're close with, it often means that you're angry.

In the example at top, the wife asked her husband "Can you wipe that up, please?" when she was annoyed. Here's another example: a mother yells at her child, who's playing with something that he pulled off of the shelf at the grocery store:

Put that down, please.