Shorting Theory - Can I Borrow My Cows?

"I'm going to ask all the questions. So firstly, tell us what shorting is." "It's all about borrowing collateral to sell something that's not yours and eventually buying it back and returning the collateral" "When you buy, you cover. When you sell, you sell short," he says. 'If I'm really, really, really,. really, really good, I sell and never buy'