One time I saw a manatee all spray painted to look like a tiger. Needless to say, the first thing I yelled was, "OH! THE HUMANATEE!"
The Humanatee
Explanation
The humor comes from a pun, combining the words 'humane' and 'manatee' into 'humanatee', which is unexpected and funny in the context of seeing a manatee painted like a tiger.