
♪ That all started
with a big BANG ♪
The Big Bang Theory Season 5, Episode 23

LEONARD: Previously on
The Big Bang Theory...
The Big Bang Theory Season 10, Episode 23

♪ Bang!♪
The Big Bang Theory Season 12, Episode 6

♪ That all started
with a big BANG ♪
The Big Bang Theory Season 7, Episode 15

♪ That all started
with a big BANG ♪
The Big Bang Theory Season 12, Episode 14