A Rough Translation

I started taking yoga (I WILL MASTER THE ASIAN SQUAT) last week for the first time ever. My Korean male coteacher, P.K., went with me and translated. I was becoming more aware of my body/mind and blah blah blah when I was startled by the rough translation "tighten your anal sphincter" coming out of P.K.'s mouth. A very ROUGH translation indeed.