Generating -5V from AAA batteries
Since I'm the one who asked you to try this in order to know if the noise in your circuit was due to the negative voltage charge pump or not...

3 brand new AAs in series will give you close to 5V, if they are a bit used it will be more like 4-4.5V but this doesn't really matter. 

When you wire several batteries in series, the resulting assembly has a "+" terminal and a "-" terminal.

If you wire the "battery -" to "ground" then the "battery +" will be at +5V relative to ground.

If you wire the "battery +" to "ground" then the batteries will be the other way around and thus the "battery -" will be at -5V relative to ground.

In both cases there is 5V between the "battery +" and the "battery -" terminals. Which means there is -5V between the "battery -" and "battery +" terminals if you turn it around.