What you're looking at below is two large pieces of heavy-duty cardboard (probably two feet in length) held together with packing tape. This contraption is used as a target for a particular kind of kick called a round kick--one person holds it perpendicular to the ground by one of the shorter ends and the other person kicks it. It makes a very satisfying *thwack* when struck correctly.
This is a round kick (image from Wikipedia.) This dude is getting a round kick to the side of the head, which can actually be lethal if done correctly. Good thing he's covering up! Bottom line, this is a very powerful kick, particularly for those (like me) with long legs.
Now, go back to that top picture. See the red streaks on that cardboard target? Those are nail polish! You can see exactly where the top of my foot hit the target each time. Nice little cluster, dontcha think?? I had to repaint both big toenails after class but I don't even mind because this is photographic proof that I am becoming a badass ninja. :)