mine. He knows.

We moved from CT where we had a "DogWatch" system to Victor, NY where we have "YardGuard". installed. The moment he saw those flags being put up, he was pretty much trained on the new one. I was surprised that he'd remember the flags even in a new place, but the installer said "no, if he's had an electronic fence before, most of them know what the flags mean."

He's pulled off some pretty impressive acrobatics in hot pursuit before.

One more story. I'm out in CT cutting the grass on my rider mower. I see 2 adult and 2 baby deer come dashing through the yard, but then they stop in my neighbors yard. I turn off the blades to just admire them for a few moments. They start to move away, just walking, not scared of anything at this point, BUT at the exact moment that I re-engage the blades, the dog comes tearing across the yard towards the deer. He hits the fence shock zone and YELPS!!!, leaping up into the air and backwards, when he had been barrelling forward at full speed, and he's pretty fast.

Meanwhile, my wife is outside in the front yard. All she hears is the noise of the blades being turned back on, and at pretty much the exact same moment, the dog letting out a huge YELP!!!.
She's thinking "Oh no, he ran over the dog!"