Apparently he came home and discovered them having a bit of how's your father in the kitchen.
idioma bit of how's your father BrEBrEold-fashioned a sexual relationship, or an act of having sex:We all suspected that the cook was having a bit of how's your father with one of the drivers.
a bit of how's your father
A playful euphemism for sexual activity. Primarily heard in UK, Australia. Jeremy snuck under the bleachers with his girlfriend to have a bit of how's your father but ended up getting caught by the school's principal.