I was running a PUG of regular Naxx with my druid yesterday. Trying out my new resto spec and healing gear. We were humming along pretty nicely when our tank announced that he had to go. One of our members started hitting General and his Guild chat looking for a replacement tank and managed to find a death knight to come help us.
Wow. Can't say I've ever seen anything quite like this. The guy was geared mostly in cloth and leather with a fairly random assortment of stats, including quite a few pieces of spellpower and mp5 gear - obviously essential stats for a death knight tank. ;-)
Needless to say, the run did not progress well from there, and we ended up calling it after a half dozen wipes on trash. A couple of us in the group tried to whisper the guy to ask if he wanted some suggestions on gearing a death knight tank, but apparently he was gearing based on how the pieces looked on his toon. To each his own!