The Admin do not prohibit roleplay of an explicit sexual nature. However, just as it is inappropriate to have sex in a public place IRL, the same goes for sex in public places on a MUSH. What you do in private, provided that all involved are both willing participants and of a legal age in whatever state or country they reside, is entirely up to you. Each player is personally responsible for making sure that all involved parties are both willing and of a legal age.
For someone to engage in roleplay of an explicit sexual nature when they are not of an age to do so is considered a severe violation of the rules of the game which if found out will lead to the player in question being permanently banned from the game.
For what is acceptable to roleplay out in a public setting (that is, anywhere outside of what could be considered private quarters), see INFO USER AGREEMENT RATING.