Why does out cat just randomly bite and hold it's teeth in us? It might happen maybe 1-3 times a week. He's a tux about 4 yrs old that we just recently adopted after spending about 4 yrs outside. We know when he wants to play he does this cause we are petting him and we get that but to sit there and randomly lock his teeth into us and not let go till we have to grab his head and pull him off is unacceptable. What's going on and how do we stop it from happening?