Was this a compliment or an insult?

[ShakyBake]

Whilst driving last week I actually waited to let someone out and politely smiled at them and they called me a baboons arse and I've been thinking about it ever since.
Baboons are known for their intelligence and cooperation, skill etc. and I was using my car to aid them so can tentatively see a complimentary link, but why the mention of arse? My car is red if relevant .
Have I been insulted for doing nothing wrong do you think?

Were you hoisted by your own petard?

That's a strange insult. Not heard that one before.
Anyway, don't waste your time fretting about what some horrible stranger said. You were being kind. They were being an arsehole.
All the kinds of arsehole. 💐

Wow, that's horrible..I'm sorry this was the thanks you got!

I think you misheard them, but I’m not sure what they really said? Hopefully “thank you so much”.

Ok I see. I guess it was an insult then. Ok thank you.

The fact you “actually waited” to let
someone out implies it’s not something you do as a matter of course as a courteous driver.
Why not, why not? (You baboons arse!)

This is the ad I got when reading your post OP. Mumsnet is shady!!

Seriously though, ignore.
I know some don't know the highway code and confuse actions, so they might have thought you thought they were impatient.