A euphemism for high class sexual intercourse with a young, hot woman (6 out of 10 or higher class)
The term is frequently used in the Greenwich, Eltham, Kidbrooke, Shooters Hill, Blackheath and New Cross areas of South-East London by a family called the Ciprianis.
Bobby; I pulled a high class slim beauty last night, went back to her flat and she gave me fish supper!
Sink; All the best to ya Bobby!
Bobby; (Haddock) Supper!
White fish liquidised in a blender has a similar appearance and taste to hot spunk. Anyone performing a blow job and enjoying the resulting eruption would be treated to a Liquid Fish Supper
Sorry we're late, Barry treated me to a Liquid Fish Supper.