Skywalking on Dust2

First of all. Skywalking's been around since Dust2 was first out in around 1999-2000. It's a simple exploit where a user can walk around on "top" of the map. You might remember seeing this in Dust in Counter Strike 1.6. At Counter Terrorist spawn. When 3 Counter Terrorists would boost until they would be Skywalking. This is not considered a "hack". Check the servers rules before using this. The only way you could get banned is if Skywalking is not allowed on the server and there's either an Admin on, or someone demo's and submits.
Anyway.. here's a great video on how to do it.
Counter Strike Source Nade Boosting.

Counter Strike Source Nade Boosting