The act of shitting into a Freddo chocolate mould, cooking it until it turns to a liquid and then putting it into the fridge to set. When it has set you wrap it up and sell it for 10p. Simples.
Ashley: "Mmm, this Freddo is so good!"
Kishan: "Why is there sweetcorn in there?"
Ashley: "Shit...it's a fucking dirty freddo!"