From Wiktionary, the free dictionary
From five + -sies.
fivesies (plural fivesies)
- A call in any children's game, such as jacks, where five actions must be performed.
1999, Susan J. Bandy, Anne S. Darden, Crossing boundaries, page 239:She had missed on fivesies, I'd missed on threesies, and this would be the deciding round.