Vienna Waterslide
Receiving oral sex by two women located on either side of the penis. Particularly length-wise tonguing of the shaft, simulating a sausage on a waterslide. Coincidentally, (Vienna,) Austria being the location where one has a very high probability of receiving oral sex.
Derek: I rode the Vienna Waterslide last night.
Charlie: That sounds fun, I've never been to a water park.
Charlie: That sounds fun, I've never been to a water park.