This, and the skull day, are my favorites actually. I can see the walking idea as entertaining because he could be extremely irritated whenever he's 'forced' to run. I actually think that the warlock has the most intrinsic role play potential. Verbally abuse your imp, /laugh as you cast rain of fire. In character you hate everyone and everything but only in ways that is fun for everyone.
My main is on a PVP server in a guild very focused on PVE progression, so the little roleplaying I do is just for entertaining myself mostly. But ever since the beginning when I was learning the classes and first found out that only hunters and warlocks get pets... I've pretended that my tauren warrior has an invisible yellow rabbit companion named russel. Russel hides somewhere in the chamber of a boss if the raid looks to be about to wipe so after we finally kill the boss i run around calling out "russel! its okay, he's dead, come back we've got more work to do! Russel! We'll leave without you".
Generally people just stand around while loot is distributed.