We've got into so many YJ nest at work that I've long ago lost count. I do remember some memorial moments though.
One was a buddy of mine that got into a nest this summer. We had tried to burn them out the evening before. The next morning we went back and there was a piece of cardboard laying over the hole that was partially burnt. My buddy walks up like a big dummy and picks up the paper. It had hundreds of YJ's hiding underneath it and they just swarmed him.
He took off running and had a big cloud of bees around his head. He had to go to the ER but he was OK. Got him 30 some odd times. We went back to get his shirt a few hours later and there was still three or four bees circling his shirt. Then YJ's are relentless.
I've also seem them get after livestock. i watched a swarm at this same job chase a gang of goats off the hill and into the barn. The poor guys were kickin and screamin.
The worse thing I've ever done is to pull up onto a nest of them while strapped in a skidsteer. All you can do is hit the throttle and pull back the drive handles as fast as you can
They usually get you because it's hard to get away.
I even have developed a fool-proof way to destroy an underground nest of them. You take a 20oz bottle and fill it with gas. You have to hit it real early in the morning before they are out. have to be real sneaky too. Find the hole, take the bottle and quickly screw it into the bee hole. Pour a little gas trail away from it and light the trail. It'll blow the bottle up in the air 20ft.
It'll knock out damg near all of them.