This took so many iterations to pin down.  One of the later iterations was the following design, which, on its own, looks not too bad.  The concept of cavemen trying to talk to each other through (clueless) turtles while sitting a few feet from each other was pretty funny.

unfortunately, when this is placed on a shirt - let’s just say the placement is a bit sketchy…

I ended up using just one of the cavemen.  I then enlarged him and cleaned up the lines so that it now looks presentable