Originally Posted by: ACHHe is pushing or pulling on the headstock but it gives a slight bend to the neck. Pulling the headstock you go sharp, pushing it you go flat. This is a real old school trick thats been around since I was a kid. No it's not good for a neck, especially a set neck. :cool:

to add to ACH...

If you're descriping the technique I'm thinking of, I think you'll find it's only possible with certain guitars. Newer guitars tend to have their necks firmly fitted to the body; however (whether by design or just lack of planning) some older guitars would allow you to push the neck away for the body, slackening the strings to produce a tremelo affect...

From my experience it is most common with fixed bridge guitars, but I'm not aware of any newer models that have this as an "standard feature"...