This is a pair of boxers comes in kids sizes only (unlike the previous pairs) It has classic running Sonic with "Vrroom" sound effect written across the blue checker background. Notice the tag though, it has the 20th Anniversary logo on it. These are Primark, & seen here directly in-store. 

This is a boxer/breif style underwear which can be found at NEXT stores in the UK area. It's done in Japanese style, with classic stock art, and Sonic's name written in Japanese beside it. The background is a loud mix of red and green, with the hot pink text and blue Sonic mixed in. The waistband (for whatever reason) says "Super Sonic" though actual Super Sonic is no where to be found. Loud though it may be, it is fantastic to see modern underwear in reasonable sizes with Sonic on it! A great item to collect.

Here's a nice pair of underwear. They appear to be either boxers or some kind of combination underwear. The checkered background fades from one color to another, without getting too loud or busy. Classic 'getting ready to run' Sonic looks good as a large design in the middle, and the classic logo is nice and large off to one side. The band is also covered in logos, while being elastic and hot green. These are made in adult sizes, and can be found in River Island stores for 9.99 pound. 

Finally, after all of the male underwear, here is a pair that's meant for girls. It has classic Sonic, but changes the logo font somewhat, and adds a pink border to it. The style is called 'cheeky'. This is available from www.topshop.com , AND it looks like they'll ship anywhere! Great news because they're only 8.00 each.

 Owned & photographed by BuzzTheBatgirl

This is the 2nd pair of busy boxers from Topman. This pair has an embroidered logo on the thick elastic waist band, what looks like 2 more bands for the legs and a classic styled design. Various Sonic stock arts are scattered around, usually seen above his name written in Japanese. The background has red blue and gray stars, plus repeated gray Sonic faces thrown in for good measure. Certainly, no one can wear white pants with these.

 Photo by Shadouge

This underwear has a fun theme of 'racing'. They've arranged the classic stock arts for Tails, Knuckles & Sonic to make it look like they're in a race. Cartoony letters say "Ready Set Go!" on the other side. It has a very basic green ground/blue sky 'background' for the scene. It's a fun & different design to collect.
These can be found at Primark in 2012, and are only about 5 pounds. (Less than other pairs) These are found in mens' sizes so everyone should be able to fit into them.

This underwear has the esame cut/style as the pair above. It may also be a Primark item. It's mostly orange, with some yellow 'rays' designs. It has classic style Sonic in spin, running with doodle-legs & regular running poses. The borders & stitching are plain blue. Photo discovered by the tumblex