Apparently the sport of tumbling was popular during The Depression. Here are two recent finds published in 1931 and 1932.
If that cover illustration on the brown book doesn't get something stirring in your loins, you aren't human.
sex act tumbling exercise is presented with detailed description and excellent graphics.
Some exercises look naughty:
Some look AND sound naughty:
Now that you're all hot and bothered, I'll let you enjoy some of the Bobs 'n Burqas cheesecake photos: