A nifty song you could actually perform in public for a young audience (and their parents!) goes to the tune of Pack Up All My Cares and Woes:

I have lost my underwear
I don't care
I'll go bare
Bye, bye, longjohns

They were very close to me
Tickled me
Hee-hee-hee
Bye, bye, longjohns

If you find them you'll know where to find me
Oh how I miss that ol' trapdoor behind me

I have lost my underwear
I don't care
I'll go bare
Longjohns, bye, bye!

--SteveF