I was unable to participate in the Tuff Mudder competition because I was to young so I created my own back yard Tuff Mudder.
Swing set slide
Slip and slide
Bunge cords, volleyball polls
It's an obstacle course for kids using things found around my house.
You can start at the gunny sack race (sleeping bag) then crawl up the rock wall (swing set slide) then whip the ropes (bungee cords around volleyball net poles) ten times.
Then race to the mud crawl (slip and slide) and if not alone, tag your partner. First team to cross the finish line (newspaper) wins.