Somebody pulled the wool over this sheep's eyes: He thinks he's a sheepdog!
The sheep's name is Jack, and it's not his fault he's confused. Alison Sinstadt and her partner Simon Sherwin, who have a farm in Shropshire, England, brought him indoors when he was just a wee lamb because he was quite small. They raised him with their springer spaniel Jessie, and now Jack is so convinced that he's a dog too that he fetches sticks, walks on a leash, and even tries to bark (though it comes out more of a baa-rk).
And putting the 6-month-old ovine in a field with his own flock doesn't help a bit: he just tries to herd them. It's positively unherd-of!