Azeris in Iran lack basic cultural rights. There are NO SCHOOLS with Azerbaijani education. People get arrested for teaching Azerbaijani turkish in their houses. You are talking about millions of people here (There are different figures on how many Azerbaijanis live in Iran – from 16 millions up to 35 millions). When you are limited in speaking your own language you become a way too sensitive to jokes about your identity. This is just a part of discriminative policy. There is also economic discrimination, too much centralization of the government, unfair distribution of wealth. Plus human rights activists in Tehran refuse to take cases of Azeri activists. Even Iranian Persian speaking opposition abroad – for example in America – is against language rights for non-Persians. I agree with the comment of April the jokes could be innocently made just for entertainment. But again, you never know how sensitive it is untill you get into the shoes of the “second class human being”.