
Apparently, he's 12-down in
the TV Guide crossword PUZZLE.
The Big Bang Theory Season 7, Episode 19

each PUZZLE will lead you
The Big Bang Theory Season 7, Episode 3

And that was the last face needed
to complete the jigsaw PUZZLE
Money Heist Season 1, Episode 8

New PUZZLE, Ma!
The Big Bang Theory Season 4, Episode 19

where the last PUZZLE gives the winner
Sheldon's contact information.
The Big Bang Theory Season 9, Episode 8