The gadget wig is a wig worn by Nicky Bluepants Altosaxophony.
After Homer was asked to go undercover, he was given the wig as a disguise. It has a fiber optic camera and a microphone in it, with a transmitter on top.
If you say "a", the camera zooms in. "O" makes the camera zoom out. "Forget about it" makes the wig self-destruct.