More than twenty one would-be-suicide bombers and terrorists from the Islamic State of Iraq and Syria had an early date with "death" when the suicide vest their teacher was using to demonstrate its use forgot to make sure there was no live ammunition. So, boom, and bye-bye. They were being instructed on how to make car bombs somewhere outside of Baghdad. About 22 were arrested, 12 of whom were wounded and 10 who were captured as they tried to escape.
Ah, poetic justice and karma rolled into one.
More here, and here.