I was in a group where during the first session our character's were separated in "the sewers" aka "a dungeon." The DM displayed the whole map for us and pointed out where our three separate groups were.
One guy didn't like being in his section and said something like "I go left, then right, then left, then right again, over the bridge, up the stairs, left, down the stairs...." That took him into a section where two other characters were on the communal map. The DM said "You don't have any idea where anyone else is."
The player said "I know. I go that way AT RANDOM and see them."
His friend told him we had cancelled the game and secretly kept playing with us.