Explain the rules of a card game to someone who has never played, in five minutes flat

Everyone is sat round the table waiting and the last thing anyone wants is a fifteen minute rules lecture before a single card gets played. This strips a card game down to what a first timer actually needs: the goal, the turn, how a round ends, and the one mistake beginners always make, so play can start almost immediately.

You are teaching a complete beginner the rules of a card game before you start playing, and you have five minutes, not fifty. Explain {GAME_NAME} covering only: how many cards each player gets, the goal of the game in one sentence, what happens on a turn, and how a round ends. Skip every optional rule, variant, and edge case that would not come up in someone's first game. Use plain language and short sentences, and end with the single most common beginner mistake to watch for. Keep the whole explanation under 200 words.