I believe the back-scratching metaphor
describes a quid PRO quo situation...
The Big Bang Theory Season 2, Episode 16
Pro tip: if you find
strong women sexy,
The Big Bang Theory Season 12, Episode 19
- Where do you stand on it?
- Strongly PRO.
The Big Bang Theory Season 6, Episode 1
FYI, part of your responsibilities
as roommate PRO tem...
The Big Bang Theory Season 4, Episode 24
- And finally, area rugs, PRO or con?
- Pro?
The Big Bang Theory Season 2, Episode 19