Here's a series of photos of a real lion-lover! He jumped into the lion's area of a South American zoo. After a slight wrestling match, the man was taken away mostly unharmed.
A marginally more detailed article can be found here. Apparently the guy tried to do a bull-fighter routine.
I seem to recall an article stating that the guy jumped in to prove that he was immortal (and was convinced he'd succeeded when the authorities removed him), but I think that was for a separate incident some time in 2003. This kind of thing happens distressingly frequently.
The story I heard was that God told the man to jump in the lion enclosure, like a Daniel in the Lion's Den sort of thing.
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