"Sexy" yoga is probably what they're calling Tantra Yoga. Tantra places some emphasis on sexual health and increasing positive energy through sexual relations. There's more to it though. Tantra is about learning to connect, whether it's with another human being or with the world at large, or with ourselves. The focus is on achieving greater understanding of what we believe, who we are, what we want in life, etc.
Here's a website dedicated to Tantra Yoga. There is enough free content here to be helpful:
Tantra Yoga Site Stay healthy,
Nancy Welker
BellaOnline Yoga Editor Founder, Nutrabeautiful,Inc. P.S. I'm liking the idea of striptease yoga though....what a concept!