It was inspired by Simon's recent party, where he handed out Mystery Shots - an assortment of alcoholic liquids served in opaque film canisters, so you can't see what you're drinking till it's too late.
White Russian Roulette requires 12 players and 12 film canisters. In 11 of the canisters is a regular shot of White Russian. In the 12th canister is a shot of breast milk.
Rupert suggested the breast milk canister could have some kind of nipple drawn on the bottom. You could all stand in a circle and take the shots at the same time, looking around at all the canisters as you drink to find out who got unlucky. It's this sort of thinking which made him MD of his own company by 21.
There followed a discussion about the rights and wrongs of drinking breast milk. Basically everyone went, "It's wrong."
Except for James Grant, who raised his head high and said:
"It would be an honour to drink Ellie Gibbo's breast milk."
Sir, I salute you.