I cantremember the name of a yaoi where the seme had a underwear fetish and cut a hole in the ukes underwear
http://www.mangago.me/read-manga/imasara_briefs_no_miryoku_ni_kizukimashita/
ooops, wrong link: http://www.mangago.me/read-manga/hidoku_shinai_de_dj_boku_no_brief_ni_ana/mi/1b2e372b7837dbf5fd23ddda9452f3a4_chapter-1/
Last extra of Hidoku Shinaide
I cantremember the name of a yaoi where the seme had a underwear fetish and cut a hole in the ukes underwear