This is a Vietnamese specialty called egg coffee. It's basically exactly what it sounds like -- coffee mixed with raw egg. It's a little bit more complicated than that though: egg yolks are beaten with sugar, butter, and coffee until stiff, then served on top of the remaining cup of coffee. According to Buzzfeed, this stuff tastes like "liquid tiramisu."
When I first heard about this, I was a little bit scared. Who drinks raw egg in coffee?! But I also knew that I had to try it, so I ordered one at my favorite coffee shop in Hanoi, The Hanoi Social Club.
After I received mine, I stirred it all together and took a gulp. It was incredibly delicious -- thick, creamy, and rich. Coffee in general in Vietnam is the most delightful I have ever tasted, so I could only expect that this would be just as amazing. And it was! If you are ever in Hanoi, be sure to check out this special coffee item. As far as I can tell, it is only served in the north, but I wouldn't be surprised if the recipe floated down to Ho Chi Minh because it is so popular.