When I was 18 and just starting college I pledged a frat.
During the "hell week" there were the various initiations and tests. One night there was the "toilet paper roll test". All the pledges were told to strip naked and then in front of everyone insert our _c_o_c_k_s into a toilet paper roll to see if our _c_o_c_k_s were long enough to stick out the other end. I've always been very boyish and small physically, including in the _c_o_c_k_ department. When I stuck my little _c_o_c_k_ in the toilet paper roll I was not surprised that I didn't make the grade. When everyone saw that my _c_o_c_k_ didn't reach through the roll there was some laughter and the pledge-master wrote "SCB", short for "small-_c_o_c_k_ed boy", in big letters on the back of my hand. After all ten pledges had been tested three of us were identified as SCBs and the other seven guys were marked as BCM (big-_c_o_c_k_ed men).
Then the pledge-master produced razors and cans of shaving cream. The big-_c_o_c_k_ed men were then assigned (in groups of two and three) to shave off all the public hair of us small-_c_o_c_k_ed boys. The pledge-master announced that after the shaving all the small-_c_o_c_k_ed boys would receive twelve swats with the frat paddle. The pledge-master also said that if any small-_c_o_c_k_ed boys were not shaved completely smooth the big-_c_o_c_k_ed men assigned to shave him would instead receive the twelve swats and the boy would not get spanked.
Furthermore the pledge-master said that if any of the small-_c_o_c_k_ed boys got a hard-on during the shaving they would get double the number of swats.
The result of these rules was that all of us "boys" got very thoroughly shaved. None of the "men" wanted a spanking so they made sure that there were no hairs left on us.
Although my _c_o_c_k_ was soft from fear at the beginning of my shave the occasional touching of my penis had an effect. As they shaved, much to my horror, my _c_o_c_k_ slowly became hard! I tried to stop it by thinking of other things but I simply couldn't. After the BCM had finished shaving me I didn't have any public hair left and when the pledge-master saw my hard _c_o_c_k_ he smiled and said that twenty-four good swats with the paddle would probably help me to get rid of my erection.
The pledge-master was right, after the twenty-four hard swats with the paddle my _c_o_c_k_ was completely soft and flopped around limply while I danced from foot to foot trying to rub the fire out of my butt. I no longer cared that everyone was laughing at my small _d_i_c_k_ - my red butt was all I cared about. As I jumped around everyone looked with satisfaction that the spanking had made my _c_o_c_k_ limp again.
The shave/spank of us small-_c_o_c_k_ed boys was completely humiliating. While us "boys" were red-faced from pain, and rubbing our sore butts the "men" were smiling and laughing. After all a paddling can be quite a bit of fun when you're not the one getting it! For the "big-_c_o_c_k_ed men" the entire initiation was a big laugh, for us "small-_c_o_c_k_ed boys" it was pure punishment!
Furthermore we were ordered to keep that writing on the back of our hands for three days. Thus everyone, including the girls on campus, could see at a glance who was a man and who was just a boy below the belt.