Brett, if you don't behave we'll give you a checkered shirt with a cat of nine tails, nice overlapping diagonal checks on your back.
A wide Crew Neck is preferred. The colors can vary and it can be short sleeved or long. My favorites are the Russian Navy surplus but oddly enough they don't seem to export the larger sizes, only the wimpy sizes for folks like me.
There are a many references to checkered shirts as there are to stripped ones in the literature, but we're plunked for stripes. We've never tried spots, but that might be tasteful. What do you think?