Alison,

You really have to be observant and watch the moat dragon on the other side of the metal detector. If they obviously zero in on you as you approach the checkpoint in the line, you can bet he/she has selected you for a "random secondary" long before you get the choice to participate or not participate in the shoe fetish.

I've found that I've been "selected" for a "random secondary" based on a couple of criteria:

1. I'm a pretty non-threatening looking 50 year-old guy. I guess they figure I'm on their side and won't put up a fight or get in their faces;

2. I often travel alone. I've observed that people who are obviously traveling alone get picked more often than people get picked out of a group. When I get within line-of-sight of the screeners, I have taken to striking up a casual conversation with the person right in front of or behind me in line, to give the appearance that we're together. Since I've started doing this, the only time I've been sent to groping is when I've chosen not to play the shoe carnival.

I'm surprised you were picked since you were obviously traveling with Mr. AofA.