A promo code, PREDICTSAIL, is being offered for a $50 bonus on the polymarket platform, with various events mentioned, including the home run derby on July 13th. However, the specific event associated with the promo code is unclear, as different outlets mention the home run derby, mlb all-star game, summer league, and nba summer league. Additionally, a similar promo code is mentioned for the kalshi platform, with a lower bonus amount of $10.