* "The new kid in class, with his thick glasses and constant book-reading, was instantly labeled a poindexter by the other kids." (This uses the traditional, often negative, connotation of "poindexter".)
* "Despite his poindexter-like appearance, he was actually a surprisingly good athlete." (This uses "poindexter" ironically, implying a contrast between appearance and reality.)
* "I wouldn't call him a poindexter, but he certainly knows his way around a library." (This uses "poindexter" more casually, without the negative connotations.)
It's important to remember that "poindexter" can be considered a derogatory term. It's often used to mock someone perceived as being overly intellectual or studious. If you're using it, be aware of the potential for offense.