Dear Max - I'm 13 and my sister is 3. We've both had "the surgery" but she still tries to get frisky with me (if you know what I mean). How can I make her understand that I'm not interested in her that way?

It might be difficult to pull off, but the best way to get a sibling off you for any reason is to fart in their general direction. They're on your bed? Fart. Trying to sit on you? Fart. Trying to hump your unhumpables? Fart long and loud. Sooner or later they all get the message.