I was 20 when I bought my first thong. I ordered it through an ad I had seen in a bodybuilding magazine. They were sheer and kind of snug, not the most comfortable. I wore them every once in awhile. I eventually bought a multipack of cotton thongs at Target, also not the most comfortable. Every once in awhile one of these would slip through the cracks (pun intended) into the laundry. I still lived at home and my mom did the laundry, but that's a post for a different day.
Later that year while interning in NYC I found Jockey men's thongs in Macy's. I bought one and had finally found a thong that looked good, fit good and was comfortable. After that I bought more and more Jockey thongs and started to find them for sale in more Macy's locations. Since then I have tried other thongs but always prefer Jockey.
During this time I still primarily wore boxers and occasionally string bikinis or thongs. It wasn't until years later that I told my wife that I was going to try and wear 30 different thongs for 30 days. After doing that I switched to wearing thongs almost every day.