Yawin's "Tennis Acca Boost" feature is designed to enhance payouts on multiple tennis bets placed together, allowing users to receive an increased return on their accumulator bets involving tennis markets. Typically, this boost applies a percentage increase to the final payout based on the number of selections in the accumulator. However, specific terms and conditions can vary, so it's important for users to review the promotional details on Yawin's website or app for particulars such as eligibility, minimum odds, qualifying bets, and any applicable wagering requirements. Always check for any time-sensitive promotions or limitations that may affect the boost.