Green’s Dictionary of Slang

silver plate phr.

[Fr. s’il vous plait; revived in campus use]

please.

[UK]Partridge DSUE (8th edn) 1907/2: since ca. 1916.
[US]Eble Campus Sl. Nov.
[US]Eble Sl. and Sociability 79: S’il vous plait ‘please’; silver plate and seafood plate.