So what is a fugue, anyway? Bach wrote a boatload of them, and many other composers did as well, or incorporated fugal elements into their compositions. Unless you've had some musical training, it can be a difficult concept to grasp (especially if you don't read music).
Daniel Pi created this humorous video explaining how to write a fugue for fun, but it's also quite a good place for the non-musician to start. In the video, Pi creates a three-part fugue, and at one point has three different versions of himself talking to the camera.
Pay attention to those segments, because he's actually performing a spoken word fugue. The first person starts, then the second chimes in with the same words (motif), then the third. Yes, it's hard to understand all three when they're talking together, but eventually they come together to say the same thing at the same time -- your cue that this is important.
And listening to a fugue is pretty much the same process. You can focus in on any of the voices, as they all are playing a melody, or take a step backwards and admire how they all fit together to make something greater than the whole.
And kudos to Mr. Pi for choice of material. I agree that Brittany Spears' pre-skank material is probably her strongest.