Cassandra: Yeah, and if a frog had wings, it wouldn't bump its ass when it hopped.
Wayne: Where exactly did you learn english?
Cassandra: College. And the Police Academy movies.
A modified form appears in the first season of the Drew Carey Show:
Drew: "hey, if a frog had wings... we'd still be screwed, but wouldn't it be cool?"
Bob: If a frog had wings...