like dots on dice

completely, quickly, and/or enthusiastically. Usually preceded by "on it..." Similar to "like white on rice," etc.

Used in expressing eagerness to do or participate in some activity or project.

Bob: Want to go to my sister's wedding? Open bar.
Joe: I'm so there. I'm on it like dots on dice.

Bob: I need the prints done by 1pm. Are you doing them?
Joe: Like dots on dice.