So the word 'whiffy' refers to it being smelly or unpleasant, and the work 'Pum' is just another word for vagina or pussy.
Put the two together and you get the gist. Usually used as a more negative adjective.
'Oi bro that cerys has a 'whiffy pum' shes ugly as'
by something gay April 19, 2020
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