Dirty Russian
A Dirty Russian is a common college prank, in which human semen is used in place of creme in a sweet cocktail known as White Russian made from vodka, Kahlúa or other coffee liqueur such as Tia Maria, and milk or cream.

* Let the semen melt before mixing it in.

* It's a crime to put semen in someone's food without their permission.
Dude, are you drinking Dirty Russian? =)