What do you wear under your riding pants during hot summer days

Guys, I was wondering as to what kind of material/apparel you wear under your riding pants to keep your yourself cooler and rash-free?

Personally, I have tried two layers of cotton shorts, which works just okay.

But is there anything that is more effective, particularly keeping in mind the Indian hot and humid environment?

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Also, has anybody tried wearing these for long riding hours?

http://www.adidas.co.in/Techfit-Cool...,en_IN,pd.html