Chill everyone
Most desi jokes are about sardars depicting them as stupid people but we all know that in reality it is not the case. Sikhs are brave people. The current Indian army chief is a sikh not to mention the PM who is also a sikh
Besides jokes are not meant to be taken seriously otherwise they won't be jokes would they? Similarly there are jokes about pathans partly I believe because pathans more than any other ethnic race in Pakistan make glaring blunders when speaking urdu..... for instance they w'd say 'kana ka liya hai' (Khana kha liya hai)...... 'yeh sarak (road) kidhar ko jaata hai' (Khan sahab sarak jaata nahin jaati hota hai etc. etc.).....then there are other reasons like niswaar, nasha, drugs etc. Not saying its right or wrong but that's what the general perception is, hence the jokes.
The one beef I have with Pakhtoons is that generally speaking they are very short-tempered (cf. Arabs) people. I remember when we were young and used to go to places like 'baara' you had to very careful when bargaining/arguing with pathans k kahin ghussey mein chaaqoo ya pistol hee na nikaal ley :)