call dibs = claim / reserve something (mainly US usage)
From: children's word to express a claim on something,
1915, originally U.S., apparently from earlier senses "a portion or
share" and "money" (early 19c. colloquial), probably a contraction of dibstone "a knucklebone or jack in a children's game" (1690s), in which the first element is of unknown origin.
Examples:
- Seven hesitates to move, and since he’s hesitant, Sekani is too. But shoot, I want first dibs on a room. “Where are the bedrooms?” (Angie Thomas - The Hate U Give [recommended!])
- ‘Good idea!’ Tom exclaimed from his side of the table, where he was pushing around some scrambled eggs. He looked like he hadn’t slept at all. ‘A specialist, maybe! Just let me call Shorty the Chauffeur. Tina’s got dibs on the Rolls for her tennis lesson at the country club, but I think the Town Car is available.’ (King - Finders Keepers)
- “If this turns out to be a pagan sacrifice,” Sam said, “dibs I not be the one to tell O’Kelly.” (French - In the Woods)