I recently ran a heroic timerunner dungeon today, and a player consistently spammed “|cffffffffTInterface/Icons/Inv_pet_monkey:275:275:0:-1|cffffffff” in chat.
This forced an enlarged icon of a monkey to load on everyone’s screen every time they did it. It was solved by /ignoring the player. But I assume this is a bug nonetheless as forcing an icon to load for a player through a chat message is most likely not intentional.