There are surely more. Feel free to post your favorite!
And now for the list…
10. It’s impossible to spend too much time in IRC.
9. Your inner voice starts referring to you in the third person.
8. You logon to drink because that’s where your drinking buddies are.
7. You know that Nick isn’t really a name.
6. You’ve never taken a typing class but still can type at 80 words per minute.
5. Everybody knows your name, they’ve just never met you.
4. Someone thwaps and you duck.
2. Someone says you are l33t and you glow with pride.
and the #1 way to tell you spend to much time in IRC
1. You’ve ever slapped anyone around with a large trout.