I was going in to a pretty remote town (I only ever saw one other player there), and it was getting pretty dark out. I was going to throw a flare across the road from the grocery store so I could see if there were any zombies, and so I could see to loot the store. I forgot I found a grenade and, being tired, F keyed to that instead. I whipped it before I realized what I did. It exploded and a player killed message appeared. I thought it was a coincidence and someone died somewhere else. Turned out his corpse was laying there. Not really any good loot but some useful stuff.