I don't know how I did it, as it wasn't on purpose, but I think Moe read the tone in my voice....he knew when I was saying something cause I meant it vs saying something in fun or praise.Dogs read our body language and tone quite a bit to decipher what it is we want, make sure your body language matches what your wanting the pooch ta do.Here are a few articles I found on the subject though:
http://www.canismajor.com/dog/hereboy.html http://www.perfectpaws.com/whytr.html