Only once.

It was two summers ago in a half-circle shaped apartment parking lot.

I was backing out of a spot and some hot-head came flying through the lot in an Expedition. (Using it to turn around, not for parking). He must have been doing 20 mph in this little parking area.

If I would have backed out a second later -- whamm!

I backed up right in front of him and he had to slam on the brakes. I proceeded very slowly while he tailgated. Finally I came to a stop so he'd back up *or* off. Well, he got out of his truck shouting obscenities, so I got out. The guy saw that I was a pretty big dude, muttered something and got back in his rig. I never said a word and merely smiled, but was ready to defend myself.