Just take it really slow dont go straight into your room and just slip your dick out.
Best way to do it is real slow. Get the message across to one of them that ou really want to fuck them. Joking and laughing is often the best way, try to kiss her or bring on the sex somehow. Dont do it infront of anyone, get you and her in the one room where you cant be seen.
Or you could set it up where she finds you wanking in your bedroom, if she walks in just smile at her and maybe she'll come in. Smile and say "Wanna feel?" as if your joking, she most likely will take it seriously =).
Good luck and post what happens!
