I think the most embarrassing mt I've done in FFXIV was one where the Night Blades and the Grim Echo were OOCing in the IC LS we have, trying to come up with a name for the celebration people have when others hit 50. "Ding party" became "Dong Party" and I MTed into Intermission "Yes, let's have a dong party."
WHOOPS.
WHOOPS.