You live for the fiber, that's all that you've got.

The story:

For years I thought "fiber" was a metaphor for having to get by on roughage or necessities instead of being able to enjoy a more fatty or "luxurious" way of living. My husband finally pointed out that I was singing the wrong lyric while we were driving down the road one day. I should have known Bon Jovi wasn't that deep. Plus, Bon Jovi could have parlayed my lyric into big money by using the song to sell certain breakfast cereals.