I came up with this yesterday when i was lvling up my friend's character in barrens. Some idiot came to me and we had this conversation:
[He] says: I hope you die.
[Me] says: Same to you *******
[He] says: btw n00b pet.
[Me] says: btw n00b gear.
[He] says: i have 7 lvl 60s so go kill yourself
[Me] says: i got 1 kickass lvl60 so go **** yourself.
You are now ignoring [He].
that wasnt enough for me so i wanted to piss him off and reported about him to GM. GM said he'll check the chat logs etc. In 5 mins GM said that i did something wrong and that they sent me an email with a warning (ehh... this was my friend's account :S). e-mail was telling that i used words **** and ******* and they sent me warning.
that means that you can simply do something to annoy person so he starts to swear and you answer him calm and dont use bad words, and then just report him.