Belgian biscuit

British. To quote the Profanisaurus, 'a vile and non-specific sex act performed by the staff of a rub-a-tug shop'.

Whatever it is it's rarely heard outside of Viz and, depending on exactly what you take it to mean, rarely seen either, thank Christ.
I offered him a Cleveland steamer and the filthy cunt's only asked if I do Belgian biscuit.
by Lord Grimcock September 02, 2007
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