If you do not know, BURP stands for Big Ugly Rock Pieces. Their is a huge controversy on the subject of BURPS. Most ADFOLs do not recommend them because you can get more detail if you build it using plain bricks. If you are building on a budget like me, and always seem to run out of bricks because you cannot dissemble any of your MOCs then BURPs are a good investment. Here is a water fall I created using BURPs.
Disguising BURPs to make them less ugly is quite easy. All you need are earth toned cheese slopes and a few regular bricks. no one will no the difference. Alas I did not follow my own advice and because of which my BURPs are easily identified, so do NOT do this!