Why do Mexicans never have Sex Ed and Driver's Ed on the same day? They have to give the donkey a break at some point.
That joke could offend Mexican folks.
They are just jokes though. I am not being serious.
I don't think you'd want Mexican folks telling jokes about your race or nationality. I think showing them the same respect would be best.
You are too sensitive. Let the pony have his fun.
It is not right to make jokes like that about the Mexican race. These types of jokes are offensive and no one is going to find them funny.