Smell their a$$ses??? :O:O Now come out of your fantasy world for a minute and tell me if a$$ is the only part that can smell in a human???? Even if you are within 10 meters of a South Indian (not all but quite a few), you can smell it and it's not really a pleasant one.
Some people in India have the same kind of stereotype about Muslims (Indian & Pakistanis) - that they stink of meat :)
If you smell one South Indian or one Pakistani & they stink, you really cannot apply that to the entire class, can you ??