Her mouth.

"Susanna I'm about to cum! " you grunt as you feel your cock and balls fill with semen.

"You better fucking cum in my mouth. I want to taste you. " she says, her mouth looks like it would be amazing to stick your cock in. And you waste no time to get your cock out and placing at her mouth, wanking off quickly to get you over the edge. She gets a little impatient and just slides her warm soft lips over it, which sends you over the edge as you send ropes of hot semen into her mouth.

"Mmm" says your dorm mate as she happily gulps down the cum you give to her, sucking your tip to make sure she gets it all. Once she is done you smirk at each other as you put your member away. She sits there and savors the taste until-

"Fucking Christ, it's cold as shite. Help me find my clothes. " she says jumping up from the cold ground. You laugh and toss her her shirt and bra and she finds her pants and panties. Before long you two are back on your way to the Dorm.