There is a well documented case of a croc getting loose in a LET-410 in Congo, getting under the captains seat and staying there thrashing. Apparently the first time the FO was allowed to land the plane since the captain had his ankles firmly around his ears. Passengers were all crammed as far back as possible.
Think it was in Vanity Fair or something like that, pretty good article about flying in the dodgier parts of Africa.