Usually a good idea: people are more complex (or illogical, or hypocritical or however you feel comfortable saying it) than merely how they voted in an election. Bipartisanship arises from assuming from a proposed group identity how every argument or choice someone makes will go.

There could be some danger to magnetic-stripe cards, especially the kind used for hotel room keys nowadays. But even there, the magnet would have to get really close.

http://www.kjmagnetics.com/blog.asp?p=magnetic-stripes

G: I thought about the diaper. It is almost inevitable.

Yes, I like that as the germ of a counter narrative.

There are numerous ways that might happen such as holding a closed laptop to your chest while you open up your backpack to put it inside. Or by taking the magnet out of the inner pocket and putting it somewhere and leaving a device near it.

Choose safety pins that won’t damage your clothes, and don’t over-complicate things.

But there’s one more issue to consider, that might be problematic. The alt-right will mock safety pins as being symbolic of diapers, and call us babies. We should have a counter-narrative available, that will go equally viral or more so. Perhaps that the diapers we’re seeking to pin are theirs, when they get all in a bunch.

I do not ever leave my cave, but will wear the pin if I do, have the kilt-pin ready, sewn on the coat. Painted with fancy sparkling nail laquer, is v. decorative.

https://www.amazon.com/Master-Magnetics-RB45CX10-Fastener-Diameter/dp/B00IYFNT4M/ref=sr_1_6/166-2753565-5872749?ie=UTF8&qid=1478974639&sr=8-6&keywords=rare+earth+magnets

Magnets. Sew a pocket on the inside of the garment at an appropriate spot. Slide one of those circular rare-earth magnets into it. That should hold a steel safety pin fairly securely and yet allow it to detach if you happen to snag it somehow.

Of course, it means you might lose the safety pin. But a 3-inch safety pin should be easy to find, at least on pavement. And in any case, it looks like they are only sold in quantity.