A hapless loser on Math Stack Exchange asks:
What is the minimum number of people in a single room so that it can be said “There are two people in this room with birthday in January ”?
Possible answers include:
There is no minimum, because the room might contain any number of people,
all of whom were born in November, and no others.
The minimum is 2, if both were born in January.
The minimum is 0, because you can say whatever you like, regardless of who is in the room.