Discouraging disassembling?

I (and I know other probably do as well) get extremely pissed off when I write a program of epic proportions, and it gets disassembled, and my code gets stolen. (This happened in class today when I wrote a 400 line code and my classmate stole all of it and somehow handed it in before me )

Are there any ways out there to pack your programs (themida preferably).

I just need a cracked version of themida essentially, or a way to prevent that from happening.

How are ur classmates stealing ur code o_O?