I walk up to that mage, wake him, tell him something like:

"Only a damn fool mage would sleep in the middle of town. You need someone to teach you a thing or two, don't you, boy? Why don't you put down those spellbooks, pick up a good sword, and I'll show you how to fight like a man."

"Hmm, those arms look a little weak. We'll need to build up muscle. Maybe a dagger first. Give up your foolish magic, it only makes you weak."

Basically give him a chance to actually *play*. He may snort at you, or cast invis, or try to attack (if he's stupid), or whatever. Maybe he'll even listen (or pretend to listen).

In any of the above cases, you're sticking to your role as a rager wannabe, but you aren't making the player in question decide that this whole MUDding thing is stupid.

(And then later on when that dark-elf destroys you at hero levels with some ubermojo that is totally unfair, maybe he'll remember that little bit of RP-instead-of-PK and return your shinies.)