Back when I was a teenager I got involved with the then-new world of collectible card games.

Now that I'm older and have steadier finances, I can actually enjoy that as a hobby, and routinely travel to larger conventions/tournaments. I also largely fund that by buying/selling cards (which is a whole fascinating market unto itself).

And I usually build a few extra minutes into my itinerary when traveling with cards:

• Binders of cards tend to show on-screen as something resembling a laptop, meaning they get pulled for manual inspection.
• Smaller boxes of cards -- especially some of the pricier ones which have a foil coating -- show as small, dense objects that the x-ray doesn't penetrate well.

So in the one case, it's something that looks like it should've come out of the bag. And in the other case it's just "generic object that the x-ray can't recognize". So I've been pulled aside for bag check enough times that I know to say "small blue box, bottom of the bag, contains cards" when they wave me over.