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1.
The "healthy" alternative to a "burger" or chicken clumps; a sandwich comprised of some sort of a fried fishy patty on a bun with an enormous dollop of mayo-AYO, available at McDonald's.
I don't feel so good...I shouldn't have ordered that McFishwich for lunch!
by Stu E. December 24, 2007
 
2.
That sandwich at McDonald's purportedly made of "fish"...my guess is it is white rubber with mayo on bread. Also known as the Fillet-o-Fish.
Pick me up a McFishwich at Mickey-D's, I need to puke!
by gourmet consumer December 12, 2007