When I was a kid, I sang the wrong words to Helen Reddy's I am Woman. In the line, "I'm still an embryo", I sang "I'm still a limbery oak."

Here's another. There was a song that came out when I was in high school called "The Night Chicago Died" I sang the title lyric as "The night she called me guy."

I won't even tell you how much I butchered Elton John's Rocket Man lyric "burning out my fuse out here alone." Too embarrassing.