Ok, so basically what happened is this: My friend loaned one of his guildies 500g to level up Jewelcrafting. Some time passed and the "guildie" now has enough money to pay back my friend. They start running a Naxx 10 together with some other people, but it goes horribly and the raid disbands, but is reformed again with the guildie as the leader, and they somehow manage to kill everything except KT. So, next day, my friend and I start up the Naxx again (the 'guildie' isn't online at the time but we can't do it later so we decide to finish it up). So, we kill KT, and later his guildie comes online and starts nerd raging (the drops were shit anyway, nothing he could have used) and refuses to pay the money back.
tl;dr: Need to get revenge on someone who won't pay back an 'in-game loan'. Not sure if a ticket would work since he "willingly" gave him the money, even if it was just a loan.