Yes, a few times on old ass cars.
One time on the highway, but luckily I was merging, and getting right off, not on a straightaway of a highway. I lost brakes and was going to side-swipe a wall between stopped cars to slow down... Clipped the side barricades and went up maybe four feet in the air as the tire caught the concrete barriers. I did bump a car, but no damage. A big phew moment. Apparently rear drum brake bled out enough fluid to cause nearly complete pressure drop.
Second time my junker car lost brakes right after pulling out of parking space in front of my home... Coasted right through a stop sign without slowing down at all. Rear brake line rusted through and bled out.
Have you ever made a fucking giant potato pancake in a 12" pan?