Sometimes it pays to respect nature, even when you think it's safely contained behind protective glass.
A group of school children learned this shocking lesson when they decided to tease and taunt a muscular gorilla during a visit to Dallas Zoo.
A video recently posted on YouTube shows the children yelling "you're ugly" at the primate, hoping to get a rise out of it.
At first the gorilla ignored the name-calling and chanting but then snaps when one of the children points a finger at it.
The children's reaction is priceless.