Hands. The bane of my existence in art school. During one drawing class, my instructor said that if we completed 100 hand studies during the course, in addition to all of our other drawings, we would get an A for the class. No matter what.
So, I think I completed upwards 60 hands before my schedule overtook me and I had to quit. HANDS! Ouch.
The one above looks like a robot hand; clearly I need more practice. This is one I did 8 years ago! Right after the aforementioned hand incident.