From First We Feast, we have one of the dumbest inventions of our time: a portable pizza pouch for those who want to buy two slices but want to eat one on the go while keeping the other on hand. I can think of a gazillion reasons why this is dumb, including the fact that you have to clean it and that New Yorkers have managed the art of eating two slices at once (see the beginning of Saturday Night Fever). It’s no longer available at the site listed, but you can get one on Amazon.
John Travolta shows you what to do at 1:35. He’s the king out there, fadda!
And you can still get this other dumb invention: a portable fork and pizza cutter combined. The object is to cut your pizza into bite-sized pieces, and then eat them with your fork, but only a total wuss would do something like that.