Easy Boxer Short Outfit Ideas! I’m wearing size large in the blue pullover and size 25 in the shorts. Size up, they run small. In the first 3 boxer shorts I’m wearing size medium. They run small so I sized up! Striped cardigan is size medium, boots are size 7. Sized up in the cardigan. True to size in the boots! Spoiled rotten hat is vibeszn. The grey cardigan is size small. Denim shirt is size small. Yellow tee is size small and blue striped boxers are one size. Sized up in the jacket to a 4! Could have done a 6.