♪ That all started
with a big BANG ♪
The Big Bang Theory Season 5, Episode 4
Previously on
The Big Bang Theory...
The Big Bang Theory Season 12, Episode 15
♪ That all started
with a big BANG ♪
The Big Bang Theory Season 7, Episode 21
♪ That all started
with a big BANG ♪
The Big Bang Theory Season 7, Episode 23