How about this one? (I didn't see it posted but perhaps it's in another thread.) You know you're addicted when you have memorized most of your airline and hotel program account numbers.

A while ago, one of my brothers asked me to get UA on the phone. He chuckled when he realized I had United's number memorized. Then my other brother predicted that once I get connected, I'll say to the UA agent, "Hello, this is Neal."