Question: What is the biggest magic embarrassment of all time?
Answer: Two words: Flash Mildew.
In particular, I would point to his work at the grand opening of the 'Tater Pig drive-in restaurant on state route 26 just south of Twin Falls, Idaho. It was a Saturday (March 10th, 1984), and Flash had arrived a bit late and more than a bit soused. His baggage was "in transit" (actually held for back rent at a motel in Billings), and he was forced to perform impromptu.
Calling upon his wits (it was a long distance call), he stepped up onto the platform. He remembered a scene from "A Connecticut Yankee..." in which the hero amazes the crowd with a feat of astronomical proportion and causes the sun to disappear. Realizing that the odds of a total solar eclipse were nil, he came up with an alternative, and announced to the crowd that they would witness the miracle of "...the full moon at mid-day".
Before he could be stopped, he made true his words. The crowd was silent for a moment, then chaos broke free. Women screamed, and men voided their entire digestive tracts. Children were struck blind. An off duty State Trooper with a stomach of iron doubtless saved many lives by taking careful aim and letting Flash have it right where the sun should never have shined with a Jumbo 'Tater Pig*, which knocked Mr. Mildew off the platform and into a shrubbery.
* A "'Tater Pig" consists of a whole baked potato thru the long axis of which a hole has been bored, and a sausage-on-a-stick inserted to fill the void. The entire assemblage is then dunked in a "cheese batter" and deep fried. No kidding!