This improv game is in the following improv game categories:
Some players will complain that everything that falls out of the sky is a dead bird (or whatever). Explain to them that this is fine too. Most players, if reassured that they really can`t go wrong, move on to other stuff after 10 dead birds or so.
A slightly less difficult version of this game can be done by having players put their hands in their pockets and take something out. Make sure they all got pockets if you want to play this game. This version is slightly easier, as anything in their pockets, like dust, or the way the fabric feels, can trigger and idea; when holding your hands out there is very little to trigger an idea.