Penis cannon:
1. A cannon shaped like a penis that fires ordinary ordinance.
2. A cannon that fires a penis instead of ordinary ordinance.
3. A cannon that fires several penises instead of ordinary ordinance.
4. Any combination of the above.
A person you hate intensely not because they deserve such hatred but because they serve as a focus for your general hatred. A healthy way to dispense with excess animosity.
Jake's not really that big an asshole. He just serves as my hate sink.