I have been to the US too. Here what i saw in typical Indian tourist there -
1. Talking loudly on the fone, no matter how clear the line is. 2. (my ex-roomies have done this ... ) not lifting the seat while takin' a pee !!! 3. Staring endlessly (at others, once eye contact is made)! 4. Unshaved stubbles (..or the pride of keeping one !) 5. Agree with roy, WALKIN INTO A HOUSE WITH SHOES ON (over time ive realised this is partly because of smelly socks !) 6. An entire family looking over one guy, when he is taking the BTS card from the vending machines ! 7. Attempts to reduce the guy to less than a shilling, while trying to bargain. 8. Using a cellphone inside a plane. 9. Saying 'No' by shaking ur hand and head at the same time. 10. Middle aged uncles doing a shammi kapoor twist in a hip hop club !