I found that question while perusing my search engine statistics today. The short answer in theory is yes. If you are a copper thief, it will most likely look like this:
That being the case, however, it is much more likely that an RF burn will result if one comes in contact with an energized antenna or transmission line. Even small RF burns are painful, large ones can be nasty things. RF burns occur because of the skin effect, that is to say, the higher the frequency of the AC waveform, the closer to the surface of any given conductor the current will flow. It is the reason why five watt STL transmitters on 950 MHz use 7/8 or 1 5/8 inch cable to reduce losses.
When a human body part comes in contact with an energized RF antenna, the body part becomes part of the circuit, thus it follows the same principals. The extremity that is making contact will have its skin burned off. It also smells bad.
Getting an RF burn is a painful lesson on what not to come in contact with around a transmitter site. But, that is not all. Simply being in close proximity to radiating elements of antennas will induce body tissue heating, just like a microwave oven. This can lead to all sorts of short term and long term damage to organs and other problems.
Therefore, the best thing is to avoid radio and cellular towers if you do not know what you are doing. Stay out of fenced in areas around tower bases. No matter how tempting that copper may look, you could be seriously injured or killed if you cut the wrong thing.