http://www.mangago.zone/read-manga/kyoushitsu_no_yugami/
http://www.mangago.zone/read-manga/hua_hua_you_long/
http://www.mangago.zone/read-manga/pick_up/
http://www.mangago.zone/read-manga/love_trial/ (2nd story)
http://www.mangago.zone/read-manga/escape_from_the_night/
http://www.mangago.zone/read-manga/kairaku_han_i/
http://www.mangago.zone/read-manga/wake_me_up/
http://www.mangago.zone/read-manga/punch_up/
http://www.mangago.zone/read-manga/i_m_falling_in_love_with_your_magic/an/i-m-falling-in-love-with-your-magic-chapter-3.html
http://www.mangago.zone/read-manga/kuroshitsuji_dj_cheshire/
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/
The Infamous Yaoi Pee-list (look for "urethral stimulaton" in the description):
http://www.mangago.zone/home/mangalist/43075/?filter=&page=1
Yaoi with urethra play please? Thank you!