Hi. Does Pinch a loaf mean take a shit ?

Yeah it does

Yes

There are hundreds of euphemisms and similes for that in British English. There is a filthy book called "Roger's Profanisaurus" which lists thousands of similar constructs but you need an exceptionally broad mind to read it. One of the few clean ones I've heard used is to describe something as "wetter than an otter's pocket".

Yep. Shawshank Redemption?

As an Australian, I've never heard it, but there are that many euphemisms, that if someone said "I'm gonna go pinch a loaf" and then used the bathroom, I wouldn't question it

Yes.

Both are vulgar, but equivalent

Yes! “Pinch a loaf” means “take a shit.” In this expression, the “pinching” is your anus “pinching off” the turd, which is the “loaf” in the expression.

I first heard the phrase on a Cheech and Chong album back in the 70s. I still use it on occasions but my current go-to phrase is I gotta talk to the Ex.

I've never heard this but that's exactly what I'd expect it to mean lol

I live in the Eastern US and have a degree in English/ESL but have never heard that before lol. As mentioned previously, "dropping the kids off at the pool" is something I've heard, in addition to "blowing mud." But these are vulgar (also mentioned already) and I wouldn't use them around anyone who isn't a close friend or relative. Edit: My husband grew up in the suburbs of a large city and he was familiar with it. He watched more shows and movies than I did growing up, as well.

Yes it means take a shit. Are you watching Shawshank Redemption?

If you've been prairie dogging for awhile, it's time to pinch a loaf!

Was it Shawshank Redemption?

While I've only heard it in movies, it's commonly understood. It's also considered to be crass. Mostly it's better to just say you're going to the restroom, no need to tell people what you're doing.

It’s an old expression I haven’t heard in years, but yes, it does.

Huh. Learned something new today as a native speaker. Where is this from? I’ve never heard it but everyone’s saying yes. Is it regional? Or just old?

also, "Drop the kids off at the pool" is a good one.

Yes! I'm from Kentucky and I've heard it before.

Is it right to say such things in public?

Yes, but I’ve never heard it as a Midwesterner. People would find it funny/weird. I’m 99% sure that it’s decipherable in the movie context though.