You're my sister and you catch me wanking into a pair of your knickers. At first you're shocked and angry but then you start to find it funny. You call me a dirty little pervert and laugh at how embarrassed I am. You ask if I have a knicker fetish and if I often go into your room to steal and sniff your knickers. You tell me to give them back and then notice me trying to cover myself up as I hand them over. "What are you trying to hide?" you ask. "Come on big brother show me your dick, I want to see it." I pull my hand away and you laugh when you see my tiny penis. "Is that what you were wanking? Hardly worth the bother." You start to mock and ridicule my tiny penis. You say that it's so small that it doesn't deserve to be called a penis or cock, it's a tiny little willy! A teeny weeny winky! You take out a tape measure and measure it, only one inch! You say it's so small you need to put your glasses on to see it properly, and can you use props like lipsticks to show how small it is in comparison. You say I must be so embarrassed! You say you can't wait to tell all your friends about this, everyone is going to know I've got a tiny little willy. All the girls will laugh at me. You say you're going to have some fun with me, if I do everything you say then you might not tell everyone about my 'little' problem. You make me repeat humiliating phrases like "I'm a dirty little pervert with a tiny little willy" and "I like to wank my tiny willy over my sister's knickers." You say a loser like me with a teeny tiny willy is only good for one thing, to be a good little bottom worshiper. You're going to make me worship your beautiful big bottom but I'm not allowed to cum. If I do you'll tell everyone what a dirty little pervert I am and what a tiny little willy I have. Everyone will know and I'll be completely humiliated. You start to tease me, bending over and showing me your knickers. "Is this what you like brother?" you say as you slap and squeeze your bum. You lower your knickers and spread your cheeks, telling me to bury my face right in your juicy big bottom. "Remember not to cum or I'll tell everyone about your tiny willy" you say. You tease me, wiggling your big bottom right in my face, ordering me to kiss and worship it. You do everything to make me cum, knowing I won't be able to help myself. I try to resist but you keep teasing and mocking me until eventually I cum and you laugh as you see the tiny load I produce. "Oh dear, now I'll have to tell everyone what a dirty little pervert you are and what a tiny little willy you have, you're going to be so humiliated" you say. Please can you use soft words like 'willy' and 'winky' to really embarrass me, and also the words 'big bottom' as they are real trigger words for me. I hope all this would be okay and doesn't sound too daft, thanks.