"Leave It"  This is my very favorite command.  Once a dog understands, you can tell him to "leave it" when he is going to pick trash up off the ground, when he is going to run up and greet a person or dog he shouldn't, when he is about to get on a piece of furniture you don't want him on, when he is bugging you while you are sitting in front of the television eating pizza. It also teaches a puppy not to chew on your hands (see "mouthing") and teaches a food-aggressive dog how to take treats gently (see "food aggression").

First, you are going to teach him to "take it". After he's good at that, you will teach him to "leave it".

• Take a tiny morsel of a favorite treat in your hand, extend your hand and tell Roscoe, "Take It". Let him have the treat.
• Repeat this several times until you know he understands (basically, open hand means he can eat it...not a hard thing for a dog to learn!)
• Take another morsel of food, but close your fist over it. Hold it out like you did with an open hand and say, "Leave it". If he reaches for the food (which he most certainly will do), hold your fist closed and your hand as still as possible until he gives up and either steps back, turns away or otherwise indicates that he really IS giving up. Then open up your hand and say "Take it". Give him the treat.
• When you know he understands "leave it", do the same exercise as in number three, but start with your hand open. Say "leave it", but leave your palm open. If he reaches for it anyway, close your fist. If he sits back, open your palm. If he reaches for it, close it. when he's really and truly given up, open your palm and say "take it". Let him have the treat.

By working through these steps, he will learn the words Leave It, and what it means.

(Thank you to Karen Clouston for the clear directions on teaching "leave it")