The PLAQUE they sent on the Pioneer probe
had a drawing of a naked man and woman.
The Big Bang Theory Season 8, Episode 21
(GRUNTS) A PLAQUE?
The Big Bang Theory Season 10, Episode 9
A couple of questions about the PLAQUE--
The Big Bang Theory Season 9, Episode 18
Well. Change "PLAQUE" to "mixed-race
couple" and you are my grandma. (CHUCKLES)
The Big Bang Theory Season 10, Episode 9