The most uncomfortable sitting position known to man. Female members of the British Royal Family, such as Princess Diana or Kate Middleton, tend to use to protect their modesty, while the male members are allowed to sit anyway they choose. It involves sitting with the knees and ankles tightly bound and slanted to one side. Not as preferable to the Cambridge cross, which involves crossing your ankles. One can only wonder how Kate Middleton keeps up that smile in public.
Bob: We’re going to a party today, sweetie. You should use the duchess slant when you sit.
Kate: I’d rather die.