Pocket Jockey simulates those carnival games where you have to propel your horse down a via any manner of hammer-bopping, ball-rolling or water gun-squirting—only here, the idea is to actually jump up and down like a horse's gallop. A firm slap to your own hindquarters (riding crop optional) delivers an additional boost via accelerometer detection. If you still have questions on how this whole thing works, why not let two lovely and tech-savvy ladies demonstrate for you in video form. The scene is on a bed and it may involve assorted panting and gasping, but yeah, it's probably SFW.
If you're still with us, Pocket Jockey will run you 99 US cents in the App Store. [Pocket Jockey (iTunes Link)]