a possum will often act dead when faced with a situation it doesn't want to deal with.
Playing possum, when someone comes to your house that you don't want to talk to, so you act like your not home.
Joe "Hey greg said he dropped over your place earlier, weren't you home?"
Darren "I was home, just didn't want to talk to him so I was playing possum!"
When your traveling with a group of guys, all sharing a room. Only a couple of the guys are able to bring home some drunken hotties. When they get back to the room, the rest of the guys "play possum" and pretend to be asleep. When the girls are naked and getting in to it, the possum's come to life!!
"Six of us were down in Miami and Bob and Jim brought home these drunk girls. We were playing possum for about 20 minutes, but the possums woke up and got in on the action"
B. Faking someone out.
Girl:Omg, he is totally playing 'possum with me. Now what?
Girl #2: just leave him alone