Haha, and my love of KfaD has nothing to do with the lyrics. The orchestration of it is just awesome. And the fun-filled attitude of the overall sound. You could put any words in there and I'd enjoy it. And Platypus is just cool.
Yeah it even says there's only a swear word in Knowledge and other than that Green Day don't swear in the "My Adventure With Green Day" story haha. Maybe Billie just pronounced some words so unclearly they sound a bit like fuck to some ears?
A lot of complaints about it seem to be from people who think he's singing about a 16 year old (I don't know if they couldn't hear the rest of the lyrics or something). I love it! A romantic and nostalgic punk rock love story.