Dancing is an excellent exercise. It gets you in touch with your body, often in an unrestricted way, and lets you show off your personality through your movements. And you might even find someone on the dance floor with whom the sparks fly.
Dancing with this new person or with your partner in a suggestive way hints to your dance partner that you want more than just a little spin on the floor. Dancing in this manner may include a lot of bumping and grinding or booty shaking of the pelvic area.
Usually your whole body ends up touching and moving with that of your dance partner, and it sometimes ends up with the woman rubbing against another leg and a man getting an erection. You can imagine how this might lead to some extra fun off the dance floor.