Shading - Styrofoam Cup thingy

XD yeah, did this in Tollner's Drawing/Painting class this past school year... he wanted us to practice realistic lines and crap, so he gave us a styrofoam cup and made us do stuff to it to make the lines interesting... SOOO... yeah... I crunched the top, and dug my thumb into the side and yanked out a chunk of it... and then of course we had to draw and shade it. XD yay.