From the Super Mario Wiki
When the player decides to stop here, they will meet Cheep-Cheep and Coach, his yellow and white Cheep-Cheep coach. His quest, Swimmin' Wimp, involves racing against Cheep-Cheep in a pool relay, but the player must lose, and make it a close race. They cannot go too far ahead, or too far behind, otherwise Cheep-Cheep will catch on and the race will automatically end. If Cheep-Cheep wins, the coach will reward the player with the Gaddget, Desktop Golf.