When the fisherman challenges you to show him a longer "Barboach" than his record long "Barboach" he will give you a "prize". Something along those lines, I don't know exactly how the dialogue went. Another guy requests a similar challenge, except he wants to compare large "Shroomish".
The innuendos are referencing man parts and lady breasts. Kind of like 90's Disney animation movies sneaking in subliminal sexual messages.