I wouldn't have anything to do with the girl unless she called the guy off. He is acting in an extremely immature manner. There is a word for what he is doing. It is "assault", and it is illegal. Alaskan law says that what he is doing is Assault in the third degree and is a class C felony offense.
http://touchngo.com/lglcntr/akstats/...Section220.htm
If your girlfriend has no problem with her beau doing this to you then she is not a friend of yours. I would tell the guy to cease and desist or you will file charges.
Don't try to tell me that it is ok for people to threaten each other with bodily harm. It is illegal and it is not a hallmark of a civilized society or person. If you and he are under the age of 18 then perhaps this is just childsplay, but if you and he are over 18 then you are messing with serious stuff.