The "zig-zag" betting strategy in Baccarat involves betting on the outcome (player or banker) that won the previous hand. It assumes streaks tend to alternate between player and banker wins. For instance, if the player wins, you bet on the player again; if the banker wins, you switch to betting on the banker. This strategy aims to capitalize on short-term streaks by predicting a continuation of the alternating pattern. However, it's based on the gambler's fallacy and doesn't alter the fundamental odds of the game.