This reference comes from Shredder, the primary antagonist from Teenage Mutant Ninja Turtles. In multiple TMNT adaptations and comics, Shredder is known for threatening the turtles with lines implying he will turn them into "turtle soup," a phrase that became a recurring joke and pop-culture reference.
The file name and recipe text are a tongue-in-cheek nod to:
• The Ninja Turtles' long-running rivalry with Shredder
• Over-the-top villain dialogue common in 1980s–1990s cartoons
• The kind of edgy, slightly juvenile humor that frequently showed up in late-90s internet Easter eggs
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