"Donald Where's Your Troosers?" is a comic song about a Scotsman who wears a kilt rather than trousers. It was written Andy Stewart with music by Neil Grant. When performed by Andy Stewart and the White Heather Group, it was a hit in 1961 and again in 1989.
Stewart wrote the song in 10 minutes while he sat, trouserless, in the lavatory of a recording studio." (wiki)