Duckman - Season 3 Episode 5
Sperms of Endearment

Bernice, Duckmans sister-in-law, decides she wants to have a child of her own. After trying the dating scene she decides to give artificial insemination a go. Due to a mis-communication and over abundance of, er, product, the service gives her Duckmans donation. Hilarity ensues as Duckman and Bernice are incompatible in every [in] conceivable way.