Great question! Mostly because the jury is still out. According to Wikipedia, DDT is a wrestling move where a competitor grabs their opponent’s head under their arm in a reverse headlock and then falls, driving their opponents head into the floor.
The DDT was made popular by wrestler Jake “the snake” Roberts. Wikipedia explains that DDT could stand for Damien’s Death Trap, Damien’s Death Touch, Damien’s Dinner Time (all named after Jake’s pet python, Damien), Drape Drop Takedown, Drop Down Town and Death Drop Technique. When asked what DDT meant, Jake once famously replied “The End.”
Wikipedia lists 40 different variations of the DDT from the elevated DDT, one of Randy Orton’s favorites, to a jumping DDT, typically done by Dolph Ziggler.
So to answer your question, we may never know.