An uncommon, solitary, sexual position where a man's penis is passed between his legs and inserted into his own anus, making his body topologically equivalent to a teacup or any other solid geometric shape with a ring attached to it. Generally used to convey the extreme undesirability of a task or situation.
Tom: "Would you believe it? My girlfriend and her family decided to surprise me at home on my birthday, just when I was going doggy style on that other chick Laura."
Harry: "Ouch! I bet you would have rather spent a whole day in teacup mode!"