Here are some boy's swim trunks that can be found at Wal Mart in 2012. As you can see at the left, they come in a variety of sizes & will be found on a rack. They have a duotone cyan/blue color scheme going on, with a faint Emerald Hill ground-style pattern, and some bright and puffy clouds near the top around Sonic's head. (sort of odd, because there's no other background detail) 

A classic Sonic's on the right of the front, and the Classic-styled logo is near the left trunk. The back is plain, just the colors and the Emerald Hill pattern. There's two navy blue pockets on each side, and the waist has a draw string with 4 holes to put it through. Photo & discovered by: Tucker Bass

Photo & discovered by: Tucker Bass