John Taylor Yezeguielian
FWIW, Taka and Reynosa Senseis explained it as
"Thank you for what you are about to show me," and
"Thank you for what you have shown me" (respectively.)
Is that also what it means when the waitress says it as she hands your order to the sushi chef?
"Thank you for what you are about to show me!"
"....uh, ok...'scuse me while I whip this out..."