When my son, who was only 5 at the time, started banging the strings of my uke, it gave me an idea to play the uke as if it were a percussion instrument. Check out my song, "Slap & Tickle" which is my version of his attempt to play the uke! I used a capo on the first fret as well to tighten up the strings for my slapping onslaught.
http://www.youtube.com/watch?v=HPnC8FCNHjE
Baron
http://www.youtube.com/watch?v=HPnC8FCNHjE
Baron