Thanks.. The salesman showed me the metal thing under the rear cargo area, but I never actually saw where it went. I just imagined it screwed into something under car.
There are times I'd like to pop that off and stick a plug in there. If people ask I would open it and say that's where I plug it in at night.
Which is why I never did. I'd probably laugh afterward and explain what it really is. I have been asked how I do plug it in, though. I know someone who put a cell phone antenna on the front license plate bumper. You can see the tip (especially if you put an antenna ball on it) which helps with knowing where the front bumper is. When people ask, sometimes he tells them it draws electricity out of the air.
The designers at Toyota are dog owners. They put a little "hatch" on the Prius bumper so Prius drivers could pop the lid and treat their cars to a good scratching under the collar.