Ooh! I do love a RIDDLE.
Oh, let me see.
The Big Bang Theory Season 11, Episode 11
Your next puzzle is a RIDDLE.
The Big Bang Theory Season 7, Episode 3
Good RIDDLE, huh?
Yeah.
The Big Bang Theory Season 7, Episode 3
"Riddle me this..."
Got it.
The Big Bang Theory Season 7, Episode 3
Okay, then RIDDLE me this.
The Big Bang Theory Season 1, Episode 10