Iv'e worn plain boxers in the past and haven't seen any like those. The only bottoms that Iv'e seen and got to wear once, were a tight water polo swimsuit, that had a long back rear zipper with a top snap. It was unusual and wore it during the warm summer months in our private swimming pool. It was fully lined inside with white nylon. I believe this swim was made in England and rarely available. It fit great and really felt good too, giving me a big healthy hard on, surprisingly being perfectly snug and secure in it. After swimming a while in our private pool, it was time to change, when my uncle with me said if I needed, he'll hep me out of it before showering. That swim suit really tickled my lowers, especially when zipped up in back and he was right, despite feeling so snug and secure in it, it wasn't going to be easy stripping it off. He just gave me a big smile telling me about those baggy button up boxer style shorts in his day. Well the time had come for my tight water polo swim suit to come off, as he firmly held me with one hand, then with his other hand fumbling with top button at my rear waist. It tickled so much, while he had me bent over, and I'm squeezing my legs tightly. Soon I heard a"pop" sound as he kept saying "hold still, it's coming off now." Now I could feel the long back zipper that ran down my behind all the way to my balls well encased in the tight wet polyester material being unzipped. Slowly he unzipped and opened the long back zipper. I could feel the tight wet swim briefs slowly separate, trying to pull them off me, yet the tight wet water polo briefs would cling to my body and my erect penis was still encased in them. It tickled so much, the snug wet swimsuit still pressing my lowers with his warm wet hands trying to pull and tug the unzipped tight wet swim briefs off me. He again told me about those baggy boxers that had gripper snaps and said he had a pair for me to wear, once he get my tight wet water polo swimsuit off. After a lot of squirming and playful resisting, he got it off me, as I let a childish yelp seeing and feeling the unsnugged tight wet swim briefs worked down my squeezed legs, then at my ankles, he won and so into the shower, hard and naked as can be. I couldn't help feeling so sexually excited, as he freed my hard erect penis and soon came on the dressing room floor, as he freed my feet form the tangled tight wet polo swimsuit. After showering, he did give me a pair of new boxer shorts with gripper side snaps. I didn't really like wearing them and were really loose on me. I really liked wearing that tight polyester water polo swimsuit. After changing, I got to wear the boxers with side gripper snaps and a few times after, still never taking a like to them. That was the last time I wore that tight water polo swim briefs with the long back rear zipper, often wondering whatever happened to them.