Unknown CALLER.
It's got to be them.
The Big Bang Theory Season 12, Episode 23
Hello, CALLER. You are on with Penny and Wil
from Serial Ape-ist 2.
The Big Bang Theory Season 8, Episode 20
...suggesting that he has
no personal relationship with the CALLER.
The Big Bang Theory Season 2, Episode 15
Need the location of an incoming CALLER.
Breaking Bad Season 5, Episode 14
We have another CALLER.
Hi, you're on Fun with Flags.
The Big Bang Theory Season 9, Episode 15