Each Tuesday, FanDuel runs a popular promotion that allows each user to bet $25 on one player in every MLB game played that day to hit a home run. Regardless of whether or not the player you bet on homered, you receive $5 in free bets back for each home run hit in the game, with a max return of $25.
Given the average number of home runs in an MLB game in 2021 was 2.44, you will receive an average of $12.20 in free bets back for each $25 home run bet you make, without accounting for the loss in expected value on the vig of the home run yes prop.
Even though home runs have been down in the 2022 season thus far, the promotion remains +EV, and there are signs that homers are trending up in the warmer months again.
If you want to learn more on how Dinger Tuesday works, here's an explainer.