I just don't see why you'd even call them Jews. How do you relate the presence of foreskin or lack thereof to a religious affiliation?
I do not agree with what he said but to answer this I believe it is bc in a society where circumcision is not the cultural norm the general reason to deviate from this would be for religious reasons and to my knowledge circumcision is s Jewish tradition, as to why they would look at there dicks long enough to see if they were cut or not and were low enough to make fun of a physical trait out of there control, of which there is nothing to be ashamed of either way, and then called them jews again as if referring to someone as jewish should be an insult, I don't know.