Roundhouse Racing, Charlotte

Whether you know it or not, you've probably already spent some time preparing for Roundhouse Racing's 5K Foam Fest. Perhaps you've zoomed down a playground slide? Or dived onto a backyard Slip 'N Slide? Grownup versions of these childhood challenges make up many of the 15–30 obstacles in this 5K race, challenging contestants to slide down a 40-foot "Death Drop" and skid across an impressive 50-foot Slip 'N Slide.

Running through them all are pits and pools of foam and mud, as far as the eye can see. Thankfully, the challenges bring ample rewards at the finish line—namely a medal, a beer, unlimited temporary tattoos, and still more messy activities. Away from the race, participants can leap into foam pits while kids bound inside bounce houses, gleefully imagining what kind of rug would really tie the place together.