Is there a way to have strangers tag my images?
Amazon Mechanical Turk is perfect for something like this.  In fact, tagging content is one of their default project types, so you should be able to just load in your images and use their template for tagging.

If you haven't seen it before, MTurk is basically a labor marketplace for very small tasks. It works best for paying people a few cents to complete very short tasks, but it is frequently used to recruit subjects for longer behavioral studies as well.