Is it normal that i get off by the idea of casual nudity

ok so is it normal if the idea of nudity being casual turns me on like when I watch porn sometimes I think about how there are people right there watching people fuck and being ok with it is very hot for me like sometimes my roommate (she is a lesbian and very attractive I am a straight man) will just be like "its hot in here" and take her shirt off and its not her boobs that arouse me its the casual-ness of it I don't know how to better explain it than that