And she's got brains enough for two, which is the exact quantity the girl who marries you will need.

The line is a characteristically Wodehousian insult delivered in the form of a compliment: the woman in question is praised as exceptionally intelligent (“brains enough for two”), but the punchline turns the praise into a jab at the man being addressed, implying he is so dim that any future wife will need extra intellect to compensate. The humor depends on social assumptions common in Wodehouse’s comic world—marriage as a practical arrangement and wit as a weapon in drawing-room sparring. It also showcases his deft rhythm: a seemingly generous setup followed by a precisely timed reversal that lands as affectionate cruelty rather than outright malice.