As a citizen of the UAE, please keep this in mind when visiting Dubai.
1- No kissing in public or PDA: It is a very serious offense in Dubai, and if a local or any Muslim man sees you, they can report you, and it is punishable by law and a fine. You are in a Muslim country. (Some Europeans may get away with it, but we take this offensively and behave appropriately.)
2. Don't swear or curse. No matter what you do in the US or Europe, swearing is very frowned upon here. I don't know if it's a serious crime, but in the UAE, if you're talking to a local or are going to swear, try to avoid it. They take it very seriously, so be very polite in your language. At most, you'll face a fine, but be careful.
3. When you go to hotels, don't say you're boyfriend or girlfriend. I tell couples visiting Dubai, make sure you're referred to as spouses. In Dubai, we highly value marital relationships, and locals might not appreciate having a boyfriend or girlfriend.
4. Decent attire: Men can wear shorts, but you shouldn't wear disrespectful clothing. I'm referring to anything that offends religions, or women wearing skirts or bikinis in the mall (especially during Ramadan). It's punishable by law in the UAE. Just make sure you dress decently/appropriately, that's all we ask, haha.
5. Drinking: Yes, you can drink in Dubai at licensed restaurants and hotels as much as you like. You can even buy alcohol upon arrival at Dubai Duty Free. But don't drink in public, and if you're drunk, you could cause problems.
6. Trains are segregated by gender. Don't be surprised, it's just the rule, so please respect it.
7. Yes, you can eat and drink during Ramadan if you're not Muslim. You're welcome, but please try to avoid eating in public during this time. It's about respecting the culture and traditions. You can eat and drink, but do so in private or in areas where you can hide your food from the locals. Nowadays, in Dubai Mall, everything is open, including restaurants. Dubai is no longer as segregated in this respect as it once was.
Also, keep in mind: locals make up only 15 percent of the entire population of the UAE. The rest are Pakistanis, Bangladeshis, Indians, Iranians, Egyptians, and a fair number of Filipinos. It's very difficult to strictly enforce this, and Dubai's rules can be relaxed to cater to the interests of the majority of foreigners. But as a general rule, if you respect our laws and rules, we will respect yours. It's a two-way street.