A runner runner in poker is when a player completes a strong draw by getting the consecutive right cards on the turn and the river. It’s also known as a backdoor draw.
For example, let’s say you have a 5h4s, and the community board reads Qs 10h 3c after the flop. If the turn and river cards produce 6 and 7, you will make a runner-runner straight since you need both of these cards to make your hand combination.
Players also commonly referred to runner runner flush draws when there are three cards of the same suit on the flop, and you need to hit the same suit on both turn and river to complete the flush.