I like really thin men, like sickly looking- ribs sticking out- like a turn of the century poet who's overindulged with absinthe and opium. But I am very aware that that is not a normal/healthy preference to have! Most of my 'pretty/ skinny' friends actually like 'big' men (not fat, but in no way thin), so don't worry- just make sure that you're healthy... Because there's nothing less attractive than a heart attack during sex.