The Pet Snake's Head

There once was a brother and a sister. So, one night, it's storming really bad and the sister goes into the brother's room and asks, "Can I stay with you tonight because I'm scared?" The brother replies with, "Yeah, sure, but just don't tell Mom." So the girl climbs into the bed and looks under the sheets to see the boy's penis and asks, "What's that?" And the boy replies with, "That's my pet snake." And the girl asks, "Can I pet it?" And the boy says, "Sure, just don't tell Mom." And the boy falls asleep and wakes up in a hospital and asks, "What happened?" And the girl said, "I pet the snake but it spit on me so I bit its head off."