Her Summer Hero(1928)

Champion college swimmer and summer lifeguard Ken Holmes saves Joan Stanton from drowning. They are sweethearts until a misunderstanding causes Joan to cast off Ken for his chief competitor, Herb Darrow. Joan promises Herb she will wear his fraternity pin if he wins the big swimming race at the hotel the next day. Despondent over his loss, Ken decides not to enter the race; later, he reconsiders when he learns that Joan is to wear Herb's pin if Herb wins. Ken wins the race and resolves his misunderstanding with Joan.