Below are the shocks for some of the countries I have visited:

Turkmenistan,

This is the most shocking country I have ever visited. Below are the shocks:

• The country in itself was a shock with the amount of dictatotship it has. From the Airport to the hotel, you will find pictures of the President everywhere.
• President of Turkmenistan built a whole city white, just because he liked it that way.

• President introduced his own Manifesto and wrote a book on it called Ruhnama. Many People of Turkmenistan still follow it.

• No taxis, but still every car is a taxi. You can simply stop any car and they will drop you and charge you some money.
• Surveillance is normal. People know it’s there and they are ok with it. No one will say anything against the government.
• People love classical Bollywood movies. Mithun is one of their favorite actors :D
• Men side pay a huge dowry to Women side at the time of marriage. Men over there became happy when I told them it’s the other way around in India. It felt like they got revenge or something…haha.
• Even with all the dictatorship, I found citizens to be happier than many other countries.
• Language! Turkmen people kind of speak Russian. So to get familiar I asked locals to teach me counting. To my surprise, the language was similar to Sanskrit. For eg. counting 2, 3, 4, 5, 6, 7, were “dva”, "tree", "chyetirye", "pyat", "shest", "syem”. After this, I looked online and found that there are many similarities in Russian & Sanskrit.
• In my initial days, I tuned into some music channel on TV. To my surprise, three consecutive songs were having Indian music. I thought this is one of the places from where Bollywood copies their music. After spending some time, I realized that it’s the other way around. Locals copy Bollywood music and turn them into local songs.
• Door to hell! well, this has nothing to do with the culture, but this thing exists in itself was a shock. Locals call it Derwaja.

China

A lot of people have answered. I’ll add a couple of points:

• People ask your age in the very first meet.
• Fire Crackers in weddings. OMG…..they last for hours and people love it.
• Men take off their clothes in restaurants. They say it’s for good digestion.
• Favorite Bollywood song is “ankhain khuli ho ya ho band”…yeah it was a shock for me :D. The “tu ru ru ru” part is what they enjoy about this song.
• People do Tai Chi in public.

United States

• In -25 deg C people will ask for more ice in their drink.
• Birthday person doesn’t have to pay in his/her birthday party. friends attending the party pay for him/her. This was pleasant though :)
• Many other …but people have already talked about those.

Vietnam

• Type of houses. Because they had to pay taxes as per the front width of the house, they built houses with small width but very long from inside.

• Vietnam Coffee. you don’t need a french press to brew a coffee.

• Coffee again. Well, coffee can be made out of Poop and people drink it. That’s Wiesel Coffee and it’s the most expensive coffee.

• Roughly half the population have the last name, Nguyen.
• People smile all the time. Probably that makes Vietnam one of the happiest country of the world.
• People drink Snake Wine. Now I don’t know much about how they are made. What I saw was that they keep snakes in the wine bottles. I asked them and they told me that they are snake wine and surprisingly they believe Snake Wine has health benefits too.

Bali (Indonesia)

• More than 80% of the population is Hindu.
• The male genital is a symbol for good luck and is sold as souvenirs.

Thailand

• Love and respect for their King.

Saudi Arabia

• Every woman has to wear abaya.
• Shops close for 30–40 minutes during all pray timings of the day.
• Men have more than one wife.
• Separate section for singles in the restaurants.
• Greenery on the roadsides in the cities.
• Saudi Arabia holds the Guinness World Record for the largest carpet of flowers. They did it in the Flower Festival, Yanbu.

Edit 1: Thank you all for such a good response! This motivated me to throw some more points. I hope you’ll find them interesting.