Guys help me out !! I'm trying to find this manga about two friends, and one of them has a...

Guys help me out !! I'm trying to find this manga about two friends, and one of them has a problem with his"thing" geting smaller so he asks the other to help him with prostate stimulation, and for the love of god i just can't find it anywhere or remeber it's name. ╥﹏╥