You’re on Definition 1 of 4Pro Tip 1/3Informal Setting Used among friends or in casual, playful situations, not in formal contexts. "Bet you can't dunk that basketball." "You're on!" Pro Tip 2/3Eagerness to Compete Shows excitement or willingness to take on a challenge or bet. "First to finish the assignment wins a coffee!" "You're on!" Pro Tip 3/3Confident Tone It expresses a high level of confidence in one's abilities. "Think you can beat me in chess?" "You're on, I've been practicing!"