Download some random music effects generater and fool around with the effects... should be something there that would make the sound different, at least.
But don't get your hopes up, chances are it's just gonna sound stupid instead.
Usually the qualitity if the output is dependent on the quality of the input, so if your voice sounds like a girl, you can probably get it to sound like a girl with a deep voice instead.
A greyscale with just one color? Heaven must surely be a dull place.
This calls for an extraordinary mix of psychology and extreme violence!
What you're looking for is a sound modulator... or more specifically, a Voice Modulator. I've had a quick look, and the cheapest solution I've found is a $15US kit. http://electronickits.com/kit/complete/surv/ck211.htm. You'll need to add two 3.5mm jack plugs to it. Check with your local electronics supplier, such as Radio Shack.