I would venture to say that my dog was as bad about this as a pup as anybody pup ever was, and I'm not kidding. But now he is one of the most gentle-natured dogs I've been around. Also obedient. I did like bruce suggested with the neck tug. By the way you said you pulled on the hair on his neck - don't do that. Get hold of the actual floppy skin. Give a gentle but firm shake and growl at him like mentioned already (don't let anybody hear you growling at him, they will think your odd, but then again, some guys will tell you to bite the dog back). Do this every single time. My dog would come back ready to kill something two or three or more times in a row before finally getting the message from me. I believe they do this because they just left the litter and did this all the time with their littermates. You just have to establish that you are not a littermate. Gentle but firm correction on an extremely consistent basis for a week or two is all it takes to fix aggression if the dog is a normal dog. Do this when the pup is aggressive. When it just is biting or play-mouthing, correct it by simply sticking your thumb in the dogs mouth and gently holding down it's tongue to the bottom of its mouth and say "no." Most dogs hate this. If it doesn't work, keep a spray bottle full of 3 parts water to 1 part vinegar in every room you ever have the pup in. Also carry one in the yard and on walks. When the pup bites or gets rough, mist him in the nose (not the eyes!). He will hate this to and immediately refrain from what he's doing. He will get the picture soon. Just be consistent and have fun with the pup and he will probably be a real winner. I've got anothernew puppy around my kennels, she's 3 months old and still doesn't have it all down. Also, on the "come" command, get ready...you may think your pup has it down, but if it is like many pups it will go through a phase around 5-9 months where it won't come for anything. Then you will need to work on some reinforcement. Good luck and enjoy the pup...and let it be a pup, too. But I would check on the crying while eating thing. That is plain sad to hear.