If you want to keep the caveman factor to a minimum, keep it covered.
Trying to remember the name of the game that featured a caveman (or rather, a caveboy) with an oversized head?
The drawing on the cover depicted a caveman eating what looked like a quarter pound cheeseburger.
The reason this is a sure-fire crowd pleaser is because humans have responded to simple rhythms like this since the times of the caveman.