Well OK Sham.....here goes....
Apprently Roy Rogers, America's greatest movie cowboy star, was doing a variety show (as was Venuti) and was waiting in the wings, mounted on 'Trigger the Wonder Horse'. Venuti was standing behind Trigger and started "tickling Trigger's testicles" with his violin bow (!!)

When Roy was announced, he triumphantly rode onstage and (just like in the movies) Trigger reared upward towards the sky while Roy waved his white stetson.

Apparently everyone in the audience was transfixed by what TRIGGER was waving, and nobody even NOTICED the white stetson!

Rick