Jackinthebox Share definition Flag What you would use to describe a Jackass if your Grandmother was present and you cared about her ears. -This guy's a total jackinthebox, he left his gf for his gf's bff and now they're cushin' it. Jackinthebox by Avalone November 6, 2007 0 0 Get merch Get the Jackinthebox mug. Buy Now — $32.95 See more merch