"Zombie Training" dream

This dream was me, my boyfriend (Jack) and our friend Greg.

Greg, Jack and myself were in this really tall, huge version of my house. But it was built more like a warehouse, no walls or anything. We were going to practice zombie training. There were all these wooden frames that looked like tree houses but just built on the ground. Greg was going to be the zombie first and Jack and I were going to defend ourselves. We climb up on to one of the wooden treehouse frames but then all a sudden Greg really turn into a zombie, and for some dumb reason Jack and I didn't have guns and I was all "Fuck!" so we're just trying to push Greg off and stuff and Greg scratched Jack and I was really concerned and said outloud "What if he really turned into a zombie even though Greg really shouldn't be a zombie." So after this I hop off the platform and Greg went back to normal, but still looked like a zombie. All dark eyed and grey. So the phone rings and some dude on the other end--apparently I knew him--asked me if I wanted to hang out and go see a Lynard Syknard concert. I was all "What? no!" and hung up. So then I go back up on the platform, where Jack is now asleep and I'm just standing and then Greg went "LOOK OUT!" and I look down and Jack is an insane looking zombie and Greg and I freak out and climb up to the top of the treehouse thing. Again, Greg and I don't have guns so we're just trying to push him off and crush Jack's head in, which was really fucked up. So eventually we get all the way to the right on the highest platform. We push him off, and watching him fall and get hurt but still climb back up. We were in pj's, boxer shorts to be exact and for some reason Greg had really tanned legs. So all of a sudden Greg just goes "13th floor?" and I for some reason knew that meant the roof. I ask Greg "Can you hold him back?! CAN YOU!?" and he ensure me that he can. So I go over to the window and open the latches and break off the screen, which was covered with ice but when I went outside I wasn't cold. I noticed he attacked Greg but he pushed him off and tried to come over to the window shouting "Let me out, I'm fine! I'm fine!" so I let him out but soon as he comes out I see Greg starting to turn more so. I just push him off the roof watching him break his neck and die and I was so scared because everyone I was with was dead and or a zombie. I scramble up to the roof top and just sit there watching a cold sunset. Then I woke up abrutly and was all "Whoa.."