Most likely, it is the following puzzle:
Six people are sitting at a table. Show that there are
either 3 people who mutually know each other
or 3 people who mutually do not know each other.
However, assuming that I guessed the puzzle correctly, I don't see why it is important that they are sitting at a table. Maybe, it makes it more intimate or something.
Regards,
Rados
p.s: this one is not difficult.