marry
What does marry mean?
Pour the dregs of one container into another so you end up with one full bottle instead of two sad half-empties. Classic move during prep or close-down: ketchup bottles, oil jugs, half-empty squeeze bottles all get married. Health inspectors hate it when done wrong (cross-contamination, FIFO violations), which is why a lot of kitchens technically ban it and everyone does it anyway.
Origin
Long-standing back-of-house slang; the metaphor of two becoming one is self-explanatory.