All we know is
they shared a cab and had a NIGHTCAP.
The Big Bang Theory Season 10, Episode 1
You wanna come in for a NIGHTCAP?
The Big Bang Theory Season 4, Episode 9
You'll join me for a NIGHTCAP
back home.
Westworld Season 2, Episode 9
Well, so am I.
Could I interest you in a NIGHTCAP?
The Big Bang Theory Season 9, Episode 24
I'm, uh, having a NIGHTCAP,
you wanna join me?
The Big Bang Theory Season 6, Episode 1