Double Nil

Before looking at his cards, a player may bid Double Nil, also known as Blind Nil. After bidding Double Nil, the player looks at his cards and exchanges three cards with his partner. If he’s successful, he / his partnership earns a 200-point bonus. However, if he fails, he / his partnership receives a 200-point penalty.
NOTE: It’s legal for partners to both bid Double Nil. When this happens, no cards are exchanged. If both are successful, the partnership earns a 400-point bonus. However, if both partners fail, the partnership receives a 400-point penalty. If one partner succeeds and the other fails, the bonus and penalty wipe each other out; the net effect is 0 points.