[For a second, John is slightly confused. It didn't seem like Sherlock to enjoy games of chance. Then he remembers the joke he'd said in passing at Hogsmeade. It's a good thing he's alone in the dorm, lest his roommates think him odd for suddenly bursting into full blown laughter.]

Only if it's the boring, regular sort of Bingo. Otherwise you'll need to give me a couple of days to draw up the special 'Stop Being a Prat, Sherlock' cards.

The free space in the center would just be "NOT GOOD" underlined a few times.