I remember once when I used to play, there were two separate basements with ladders leading down to them. I got the idea to get another person, and go into the basement and then have another person put a bookshelf and some couches over the entrance, locking us in; however, it turns out that the person who had just sealed us in turned into the zombie

we were the lucky ones.
Later that round I told another person to go down in there, and he turned into the zombie after I had made it so he could not get out. So of course I'm ecstatic and call the whole team over. Unfortunately, the joke only lated for a few minutes until the survivors started shoot at the head and hands of the zombie as he was trying to get out, resulting in him getting stuck in some couch at the very top of the ladder, allowing him to teleport out, then slaughtering us all.
I wont forget that though :P