mine was when i was in this OP pvp battle the guy i was aginst and an OP sharp V
fire III sord.After i died like 3 times and went through 3 sets of diamond armer.i finally killed him.he had a ton of potions and when i was trying to find the sord a noob that just joined cam by and PICKED UP EVERYTHING!!!! i never got it back.
my second wors is when i was moving to the nether i had so much OP sords and armer
then i had to go so i logged out. when i csme back on I WAS IS LAVA idk how it happend but i lost everything.