Be ready to see people making out in the open, on the streets, in the metro stations and inside the metro standing beside you.
The food is generally bland, deal with it.
also "making out" here would be petting, not sex...
food here is not spicy, but it is made with fresh, good quality ingredients (the sandwiches are awesome, imho). and the variety of food you can get in santiago is increasing (when i first arrived here, over a decade ago, there was just one indian restaurant - now my favourite place to eat is russian!)
Overall, I didn't have a culture shock after coming down to Santiago. The only thing that really surprised me is that many young people don't speak any English.. You can get by any where in Asia with English but it's different in South America.
Also, you can buy Arsenaloye beer in Jumbo/Santa Isabel supermarkets at the moment, if you miss that... :o)
It shouldn't be a culture shock for most people on HN.
Shiv Sena doesn't exist outside India.
Chileans also aren't used to meeting foreigners so in areas outside of Santiago - foreigners are kinda treated like celebrities.