Basically a threesome between one guy and two white girls in which all three participants are extremely close together at all times. This allows for the sharing of many bodily fluids, such as saliva, cum, and vaginal fluid. A more literal form of the white girl sandwich is when the heavier of the two girls is on the bottom and the lighter of the two is on top, with the guy sandwiched in the middle. Though it may seem overwhelmingly disgusting at first, it truly is an incredible thing that should be experienced at least once during a person's lifetime.
I'm probably gonna get myself a white girl sandwich on Tuesday, which would be the dopest thing ever.