Wow, that's just downright disrespectfull. However, he may think that this is okay since you guys are friends, maybe you should try telling him directly.
I have a friend who blazes me all the time, but I never disrespect him like that. I never tell him to pack another bowl, and I always thank him for smoking me. Everybody wants to be resepected, and friends should be especially respectfull with each other.