A boy emu in America called Fren is guarding a green ball, because he thinks it's an emu egg!
Unlike most animals, it's the male emu's job to look after eggs, and sit on them until they are hatched.
Emu eggs are green, so when someone threw a green ball into Fren's pen, the huge bird thought it was an egg and starting sitting on it.
Fren made a nest with some hay to look after the ball, and won't even leave it to eat his food!
Usually, emu eggs take 40 days to hatch, but it looks like poor Fren's in for a long wait.
Fren made a nest for his egg-ball!
His owner Rebecca said: "It takes 40 days for an emu egg to hatch, and it hasn't been 40 yet, so he's not getting suspicious.
"We're going to have to take it away from him, which will be so sad, because he's such a good dad," she added.