Heh. It might be considered collusion if it was a tournament game. It might be considered cheating if it happened 300 times in the space of two days. It may even be against the spirit of the law in that it could effect your rating in a way not determined by your skill at the game of chess.
I wouldn't worry about it though.
...if i do not capture a piece in a rated game and allow my opponent (who is a friend) to move the piece out of harms way?
i was going to let him do so because i really don't care and i just wanted to play the game for a bit. however, if it is considered cheating (since you can argue that it's changing our ratings), i won't do it.