I think everyone involved in a discussion using actual measurements should have checked wikipedia on this at least once before. The lifestyles study (professionally measured, but self-selected sample so it might even sample guys bigger than the true average) has cumulative distribution graphs here:
Fileenis circum percentile.svg - Wikipedia, the free encyclopedia
Just look along the bottom for where you are, and where the blue line is on the left side is the %age of men that size or below. So if you're 5.5" you're in the top 10%. Barely anyone is above 6" (less than 1%.) Granted you'll find some guys around here in that range, but thinking you're small since they're bigger is like a 6'4" guy thinking he's short because Shaquille O'Neal is taller than him.
About 70% of guys are under 5" around, so 5" isn't skinny at all, and a full quarter of guys are between 4.75-5.0, so this is easily the most common size. This study was 300 people, and only 1-2 of them were above 6.5" around