from wikipedia:
"A study conducted by LifeStyles Condoms during 2001 Spring Break in Cancún found an average of 12.6 cm (5.0 in) with a standard deviation of 1.3 cm (0.5 in)."

heres a chart:
http://upload.wikimedia.org/wikipedi...nis_circum.jpg

im suprised that apparently the same percentage of people have a 5.5-6 thick one as do an under 3 one.... poor guys... i cant even imagine one like that actually... *looks for pictures*