From The Collaborative International Dictionary of English v.0.48:
dibs \dibs\ (d[i^]bz), n.
1. A sweet preparation or treacle of grape juice, much used
in the East. --Johnston.
[1913 Webster]
2. A small amount of money.
[PJC]
3. A right or claim, such as the right of use, or of first
choice; as, I have dibs on the binoculars after Jim is
finished..
[PJC]