
"Leonard, call me
if you're interested in COITUS.
The Big Bang Theory Season 4, Episode 6

you haven't had COITUS on?
The Big Bang Theory Season 7, Episode 18

the obvious answer is,
they engaged in COITUS.
The Big Bang Theory Season 5, Episode 1

Also, if they did have COITUS, we'll
all be needing a skilled psychiatrist.
The Big Bang Theory Season 10, Episode 1

Technically,
that would be COITUS interruptus.
The Big Bang Theory Season 1, Episode 1