Do it. Don’t think, just do

I, too, would be speechless if I saw someone with a foot full of thumb tacks.

Won't remember how much your back hurts when your foot is falling off

Technically not entirely incorrect, although poorly implemented. If they're talking about what I think they're talking about, it's acupressure/distraction therapy. You can buy "beds of nails" to accomplish it (which are less intimidating/awesome than they sound). Basically a somewhat padded mat. One side is covered in circles that have rigid plastic spikes protruding from them (usually like a dozen spikes to a circle or so). You CAN stand on them, but you can also just lay on them. They supposedly can help treat a myriad conditions.
http://iheartgiveaways.com/wp-content/uploads/2013/12/bed_of_nails-7.jpg

Warning: graphic
https://youtu.be/x3mvWzBG9qU
This guy sure as heck doesn’t have back pain anymore