Mugga Wugg Chapultepec is the name of a Peruvian rain god, at least according to the April 23, 1964 broadcast of The Jimmy Dean Show. Rowlf brings back his mask from the New York World's Fair in Long Island, and discovers the inscription on the back. His name translates as "Bow to me or I'll flood your basement."
When mentioned by name or occupation, thunder and lightning indicate a beckoning storm. At the end of the show, Rowlf impersonated the rain god, saying "Stay tuned to The Jimmy Dean Show or I'll ruin your next picnic." (Again, signs of rain manifest.)
Chapultepec is an Aztec name, actually used for a park and castle in Mexico and not Peru.