Dundee Pregnancy Method

Alright, listen up, you big dummy. This 'joke' is what we call 'dark humor,' but mostly it's just super offensive and gross. A 'slag' is a nasty word for a woman who's considered promiscuous, usually in a bad way. 'Dundee' is a city in Scotland. The 'joke' implies that women from Dundee who are called 'slags' are so unhygienic and desperate that if you, the dummy listener, were to ejaculate ('spunk') in a gutter, flies would pick it up and deliver it, thus impregnating her. It's dehumanizing, sexist, and relies on negative stereotypes about a city and women. See? Not very funny, just crude, like your brain.