Rhubarb and custard 

A euphemism to describe the oozing from and infected orifice.

Doctor I don't know what it is, but it looks like rhubarb and custard.

Rhubarb and custard by The curious bibliophile July 9, 2018

Rhubarb and custard 

The act of sticking a piece of rhubarb into your vagina whilst someone nuts onto it

Me and Jeremy did the rhubarb and custard last night

Rhubarb and custard by Boobmaster January 16, 2022

Rhubarb and Custard 

A form of pill popular in early 90s rave culture, where extacy was supplied in yellow and green capsules, named after a popular song at the time. see also Dennis the Menace

"Hey man, what you got"
"I got some Rhubarb and Custards, deck one of these and you will have eyes like dinner plates"

Rhubarb and Custard by Jules W December 17, 2008