Story time. Some weeks ago I was casually playing, nothing unusual. My ping is fine, we are all hyped up on our team - when the unimaginable happened. I flashed before the minions even had time to spawn.
What followed was a long row of _???_ pings in the chat. Welp, must have pressed it accidentally, though my finger wasn't really that close to my flash button.
But now, instead of it happening once, it kept happening throughout the game and the next few to follow. Players thought I was trolling though I was just as confused as them. Turns out that I had crumbs inside my mouse that kept setting off the key for flash. How'd they got there? No idea.
Moral of the story, don't ping when your teammate accidentally flashes at start of the game - they might just have crumbs in their mouse.