Too slim

Im practically 6 ft and all my friends point out that I'm "so skinny" and since I have long legs they make jokes about how long they are and they could just snap if they kicked me. At the start I didn't mind them talking about it but now it's just gotten out of hand, not sure what to do and I'm really insecure about my height and weight  all I want to do is fit in and not be towering over everyone. Does anyone know any tricks to lowering ur metabolism???