steam turbine
Refer's to a sex session where the movement begins slow, and as the man and woman begin to sweat more, they are driven to increase the tempo, power, and volume of the sex session until one of them achieves an orgasm of such force that it causes one or both parties to release a "WWOOOOOOOOOOO" type noise, and both seize up due to muscle fatigue.
I was hoping for a simple quickie.. but after things got going.. it just turned into a steam turbine and we couldn't stop ourselves! And that is why I have charlie horses in both legs.