The word is voilà, as in “surprise!” Or, literally, in French, “see there,” not, as many seem to believe, just a random sound that people like to say, which is spelled a variation of “walla.”

It’s not “once and a while.” It’s “once in a while.” In. IN.

And while we’re at it, it’s “up and at ‘em.” Anything else makes absolutely no sense.