
The THEORY is that
if you really tax your brain,
The Big Bang Theory Season 10, Episode 22

and string THEORY sound
like a relationship,
The Big Bang Theory Season 7, Episode 20

Previously on
The Big Bang Theory...
The Big Bang Theory Season 12, Episode 15

Meme THEORY suggests that items
of gossip are like living things...
The Big Bang Theory Season 4, Episode 20