it's on

be on (one)

1. To be one's fault or responsibility. This whole mess is on the sales department, not us! Fine. But if this goes wrong, it's on you. The mix up is on me, OK? I'm sorry!
2. Of a drink, meal, performance, etc., to have the expenses covered by one, especially as a gift or benefit to someone else. A: "How much do I owe you for the tickets?" B: "Nothing, it's on me." No, no, the meal is on the house—the boss insists.
See also: on

it's on

An exclamation of readiness, eagerness, or anticipation for something, especially a competition or confrontation. He said what behind my back? Oh, it's on! The other team is really picking up momentum, it's on now.
See also: on
Farlex Dictionary of Idioms.
See also:
  • mess with
  • mess with (someone or something)
  • mess with someone/something
  • mess of
  • mess of (something)
  • a hell of a mess
  • hell of a mess
  • if you want it done right, do it yourself
  • if you want something done right, do it yourself
  • if you want something done well, do it yourself
References in periodicals archive
Normally it sells for pounds 9.99 but it's on offer at superdrug for only pounds 4.99.