Re-post from the other thread:
You listen to them (or a Zeppelin-related song) 24/7 for the last 7 months. And when you listen to another song by another band it just doesn't seem "right".
When you're not listening to them, you're watching them on DVD or on your iPod, and when you're not doing that, you're reading about them in any sort of biography that mentions Zeppelin.
You buy Zeppelin shirts that prominently display the band members faces or name and purposely don't wear a jacket outside so you can show off.
You spend a small fortune on concert tickets to get the best possible seats just so there's a chance a certain band member may look at you.
In more than one conversation during your day you mention the words "Led Zeppelin" or "Robert Plant".
I uh... know someone like that.