Two hunters are out in the woods when one of them collapses. He doesn't seem to be breathing and his eyes are glazed. The other guy whips out his cellphone and calls the emergency services. He gasps: "My friend is dead! What can I do?" The operator says: "Calm down, I can help. First, let's make sure he's dead."
There is a silence, then a shot is heard. Back on the phone, the guy says: "OK, now what?"
HAAAAAHAHAHHAAAAAAA! Hilarious! The study, however, does say that this had the best general response. There are lots of jokes that you, specifically, might find more funny than this. So, from an analytical standpoint, the joke above is the best mediocre joke ever.