From CNN:

BELGRADE, Serbia (Reuters) — A 23-year old Serb was found dead and half-eaten in the bear cage of Belgrade Zoo at the weekend during the annual beer festival.

The man was found naked, with his clothes lying intact inside the cage. Two adult bears, Masha and Misha, had dragged the body to their feeding corner and reacted angrily when keepers tried to recover it.

“There’s a good chance he was drunk or drugged. Only an idiot would jump into the bear cage,” zoo director Vuk Bojovic told Reuters.

Local media reported that police found several mobile phones inside the cage, as well as bricks, stones and beer cans.

See kids, this is what happens when you get really drunk and think it might be fun to jump into a bear cage. I like that they actually included the quote from the zoo keeper saying that only an idiot would do that.