An album from the rock group Spinal Tap.
Marty: "The review for Shark Sandwich was merely a two word review which simply read shit sandwich."
Something bad; awful; disappointing.
Coming from This Is Spinal Tap, when the band's CD "Shark Sandwich" is referred to in one review only as "Shit Sandwich".
"That movie sucked big time. It was a Shark Sandwich."