Best bit is with those colours you could create an infinite number of bro-bordered pool segments with each bro-bordered segment sharing a side with no other segment of the same colour.
Well that's also true with 2 colors if the bros just make a checkerboard pattern.
What you mean is that an arbitrary number of bros could section the pool into any arbitrary collection of shapes and with only those 4 ball colors you could guarantee there's a way to fill the sections where each bro-bordered segment has a different color on either side.
If anybody ever asks "what would happen if you put a group of ADHD dads in a pool with pool balls and gave them half a beer each?" then show them this picture
I will save this image for the very likely situation where someone asks this exact question. Thank you for the suggestion!