Really Weird Behavior

Ok I have a 2 year old male cat, who's really sweet and cuddly, he sleeps in my bed right next to me but lately when I'm petting my cat he start to make weird sounds and raps his arms around my arm and bits my wrist and try to mount my arm!!
Why? and how do I make him stop?

What he perceives when you pat him may be some dominance coming from you (imagine being patted on the head so much :0) and it also may overstimulate him after a time, so he's trying to tell you to back off. Try to shorten the activity according to what he seems to tolerate - break it into smaller periods.

One of mine does that, he tells me thats enough petting. I tell him he's an old crank.