
And the policeman says, "Did you know
you were going 85 miles PER hour?"
The Big Bang Theory Season 10, Episode 21

of 4.6 yoctometers
PER femtosecond.
The Big Bang Theory Season 5, Episode 18

has to be four revolutions PER second.
The Big Bang Theory Season 10, Episode 20

Well, no, not PER se, but...
The Big Bang Theory Season 4, Episode 1

Per our roommate agreement,
kindly refrain from raucous laughter...
The Big Bang Theory Season 4, Episode 24