|Dibs on the table!|
Commonly used as:
"Dibs! I saw it first!"
"I've got dibs on the blue chair."
Of course, calling dibs is usually informal at best, childish at worst, so it's not something you'd do in front of your boss. But it implies a level of camaraderie, and a willingness to uphold loose verbal contracts; calling dibs means you trust those around you to respect your claim.
It's a clear statement of intent, too: "I want this." But because it's so casual, it's not often taken seriously.
If a character declares dibs on something, you expect that the thing desired is not of vital importance. Villains might call dibs on inappropriate things--calling dibs on a romantic interest, for example, clues you in the character thinks of the person as a trophy instead of a person. It's also a way for a character to both hide and reveal a true desire: by trivializing the object of interest, it seems as if it holds less importance than it really does.
Have you read any characters who call dibs on something lately? What did they call dibs on, and what does it say about how they feel about the subject of the dibs and the people around them?