my little theory is that jason shaved his head and changed his clothes during the time between 2 and 3 maybe to avoid the cops (he was still human) because during the start of 3, you hear the reporter on the radio talking about the murders that occered in 2..
-or-
there is always that crappy continuity error that happens between each one B)
he started thinning on top and it bothered him a little, then he started noticing girls who loved guys who shave their heads were sluts most of the time, so he figured \"what the heck\" The when he started to get more and more P*ssy he decided never to let it grow again.
..oh wait that was me :lol: