Back in TBC we did heroic Shadowlabs (When you couldn't kick people from your group if your weren't the leader), our tank (and group leader) said "AFK sauna" and went afk -.-. And as we only had one boss to go we all went afk as well until he got logged off, we got a tank and finished it :P
[Me]: Hold on one sec, it's hot in here, gotta open a window
[Me]: Oh dang, hold on, I hear a swarm of bees outside, gotta close the window
[Me]: OH GOD OH GOD THE BEES, OH GOD THEY'RE IN MY EYES, AAAGGGHGHGHGHGHGHG HELP ME AAGGGGHGHGGHHHHGHGHG AAAGAAAAAAHAHHHH!!!
I once used "AFK my neighbours house is on fire!" during the lead up trash to Kael..... It actually was on fire, half the neighbourhood was there with hoses trying to keep it in check until the fire department showed up. Being the main tank at the time the raid didn't have a choice but to wait for me....