What is Border Collie?
1.
Smartest breed of dog in the world. They make great companions for people who can excercise them physically and mentally. However a border collie with the wrong owner can easily become a problem dog with neurotic behavior.
My Border Collie is smarter than your honor student.
See
2.
(n) Used to describe someone whose positive attributes, such as enthusiasm, friendliness or good looks, are completely undone by their mind boggling stupidity. The type of person who would do anything to please you if only they could remember what it was. Or who, in their excitement, is likely to urinate right where they stand if you say something nice to them or feed them a snack.
"Mate, that bloke's got a touch of the Border Collie about him."
"She was up for it, but I had to walk away when she went all Border Collie on me."
See