Infinite NPC's From Pandaria Quest (Patreon)

The quest "Holed-up" from Sya Zhong (Kun Lai summit, 43, 88.2) in Pandaria is a quest where you escort four pandas to safety. If you begin the quest while in a raid group, for example by porting out of LFR without leaving the group, you will find the quest dialogue for each NPC can be repeated indefinitely creating potentially infinite numbers of NPC's. 

There is probably no particular utility I'm aware of in doing this as the pandas do not attack and cannot leave the zone, unless you wish to crash the server (not recommended as it results in a permaban normally).  I say "probably" because it is possible there may just be some interesting interactions between the NPC's and pet classes which have abilities or traits dependent on the number of minions they have.

That said a lot of fun and makes for some impressive screenshots.