Literally search "Battlefrog League Championships" on YouTube. Battlefrog is an obstacle course series. The League Championships are coed relays, and one of the women's obstacles is a nice slide into muddy water. YouTube has several videos and it will also air on ESPN2 (US) tomorrow night at 9 and 10 PM.

Not that messy, but I was surprised to see it at my local sports bar, and I liked it. Worth checking out if you like mud and/or wetlook.