Spare buttons

After a solid month of wearing nothing but comfy stretchy clothing for my yoga teacher training, I got dressed in "real" clothing today to go into an office place to meet a friend for lunch. The professional-looking pants I put on have a spare button sewn on the inside and on noticing it I paused in thoughtful appreciation: should I ever lose one of the buttons (burrito-provoked or otherwise), I feel reasonably sure I will be able to locate the replacement. In contrast, the button and extra thread orphanage I've got going at home is not likely to ever be the source of the spare button that I actually need. This little design detail got me thinking:

What other items would it benefit me to have attached to my physical person or clothing?

I could start small, maybe pinning a few safety pins inside every pair of pants just in case.

And this winter I might bring back the classic mittens-on-the-end-of-my-coatsleeves.

And what about discretely affixing a few bandaids to the underside of the sole of a heel where it doesn't touch the ground?

There are already some product designers out there thinking like this. Cheers to Reef, who has made some important progress in this area by putting flasks in the soles of flip flops. Yet the Swiss have let us down: where is the Swiss Army hair clip, complete with corkscrew?

Surely I am not the first person to have thought of this.