A rule where a dealer blackjack also takes your doubled and split money.
Bad for the player; it raises the house edge by about 0.1%. Example: you bet 10, double, and the dealer has blackjack; you lose all 20, extra money included. The chart differs at 11 vs 10, 8-8 vs 10 and A, and A-A vs A, which all become hits. One of the rules to check at a standard table.