"The Andrew Sisters, a three part female harmony group popular in the 30's and 40's, sing '6 Jerks in a Jeep that leaps'... This is taken from the public domain movie Private Buckaroo made in 1942. It's a good sing-a-long tune and the harmony is quite amazing."
http://www.pdcomedy.com/Movies/Andre...ksInAJeep.html