While during anal sex between two gay men, the man who is the pitcher pees inside the catchers anus.
"Man i clicked on this link in my email that said get a taste of Maui. Thinking I won a free trip i clicked on the link and it was just a photo of one guy giving another guy a Mango Maui Surprise."
Refers to a certain bitter/sour taste that a mango gives off. Can be used to describe any kind of fruit, not limited to mangoes.
Bob: What's wrong with your mango?
Tom: It tastes weird. Like bitter and sour at the same time.
Bob: Oh, they call that mango wang.
Tom: Now that you mention it, this mango does have some sort of wang to it.