Anybody ever heard of this term? Coining (kerokan) is a traditional way for Indonesians to help you feel better when you feel that you have a gassy stomach but you can't let the gas out through natural ways. You use a coin to scrape your back (actually someone else has to do it for you) and make diagonal red lines all over your back (so it looks like you draw a red skeleton on your back). Normally you rub some oil/balm first diagonally from the middle to the left and right of your back before scraping it with a coin. Once you're done, you'll feel WARM all over your back and usually you can (sorry) fart again and it'd feel good. :-))))
Obviously foreigners would consider it a nasty habit. My own husband think it was weird. Here's what happened. Yesterday it was SO sunny, so I decided to take a walk wearing my new summer jacket I wanted to test. The jacket wasn't wind-proof, but it was warm enough to walk outside when it was around 12'C. I even began to sweat a bit afterwards. However, during the evening I started to have a slight headache (I HATE headaches) and my stomach did feel gassy. I knew when I needed coining, as my Mom used to do it back home. I tried taking a ginger tablet to help me let out the gas, but it just whirled around inside my stomach (yeah, I could hear the noise). So I asked my husband to do it for me.
He looked at me weirdly, even though I had told him before we were married that I would need his help to do it (I'd sent him a picture of what it looked like) if I ever needed coining. After some begging, he finally relented. LOL! Funny thing was that the first time he did it, he rubbed some balm across my back from the center to the left, then he scraped it with the coin just ONCE!!! I told him to do it over and over again to make red lines. He didn't want to hurt me, so he started to scrape me REALLY gently. Naturally I asked him to do it harder and harder. He said, "Oh dear, you're a masochist!" NOOOO, I'm NOT a masochist but that's the way coining is supposed to be done. :-)))
After he finished doing it, I joked to him, "Well, now I can tell people what you've done to me and show these red marks."
He replied, "Yeah, right, and then they'd take me to jail or something 'coz they thought I'd hurt you."
Funny stuff happens when you try to introduce a traditional thing to another person who's not used to it he he...Oh yeah, scientifically speaking, coining makes you feel good 'coz when the coin scrapes all over your back, it actually presses some acupuncture points on your back.