I got the random beep last night at ORD. It kind of made up for the fact that there was no one waiting ahead of me in the PreCheck lanes.

I heard the long beep. The screener immediately advised me that no metal was detected and he'd explain it to me. I responded that I knew that it was a random selection. He seemed to be somewhat surprised that I was aware of what it was.

He summoned someone to check me. I was given the option of going through the whole-body scanner or having a pat-down. I chose the scanner. I was asked to remove my sportscoat, but allowed to keep my shoes on. He held my jacket for me during the scan. My upper left arm alerted, right under the loose short sleeve of my polo shirt. He could have easily peered under the sleeve, but patted it down. He then checked my jacket pockets; I had a KN95 mask in one a glasses cleaning cloth in the other (he asked me if I had anything in the pockets, and I told him).

The whole process took a couple of extra minutes. At all times I was allowed to maintain visual contact with my carry-on bags, where I had my wallet and cellphone. As I was collecting my bags from the x-ray belt, I saw another passenger, a woman, being subjected to the random screening. It must have been a slow night.