South African slang used in some parts of the country. Describes a situation at a party / get-together / social gathering where most of the participants are men, especially those in their middle-ages and a bit older. Not necessarily a sausage fest of older men.
In a stereotypical setting, jazz and soulful deep house is the order of the day, expensive whiskies and brandies pouring, and a very decent collection of cars assembled. A small number of women may be there, sometimes wives / girlfriends of some of the participants, or young women being courted.
Piet: "Isn't Sipho holding a chill session or something? We should go I'm bored."
Angelo: "I walked past his house and it's father's day there. Not for me bra."