Poine Dexter?

Can anyone tell me where the american expression ‘Poine Dexter’ (spelling?) comes from? I suspect it might be an old TV character or something but I really have no idea.

I don’t know of any such expression. Perhaps you’re referring to using the name “Poindexter” to mean something like “nerd” or “upper-class twit.” It has to do with the association of the name “Poindexter” with overly studious chaps and, well, upper-class twits.

One theory, from a British site yet:

Thanks bordelond, that looks like the daddy-o!..if the character was named after the word was coined then where did that come from?

Another slightly different take, with the Felix the Cat connection in common:

In my first cite, the author only speculates that “poindexter = nerd” was in use before Oriolo created the Poindexter character. This site, on the other hand, puts forth (with the “allegedly” caveat) that Oriolo named the character after a real person.

Most sources say that the character Poindexter was not introduced until the animated television series in 1958, not the 1920s. Considering that Joe Oriolo, credited with creating Poindexter, was born in 1913, the 1958 date does seem more likely. The inspiration for Poindexter is said to be “[Oriolo’s] lawyer, Emmet Poindexter … a short, intelligent man who wore heavy black glasses.”