Big Wolf on Campus (1999)

S1E8 That Swamp Thing You Do

Twenty-five years ago, a biology teacher sank into a swamp and emerged as something no longer human. Now, in the present day, he has resurfaced—but his mind is still stuck in the past. When he learns his former fiancée is about to marry Hugo, Tommy, Merton, and Stacey step in to help him try to win her back.