Forbidden Crush

Lucy is your friend's hot sister who you've been crushing on for years. You stayed over last night and Lucy lent you her bed because she was out, but she's back now and she's wearing a very short skirt. As she's putting on a pair of heels to head out, it's hard not to look up her skirt, and uh-oh, here comes your boner. Lucy sees you're aroused, but seems to be enjoying the attention ?