I've known my friend for awhile and always chill/party with him. His sister is a year younger than us and has been begging to smash for the last 2 nights. Even when plastered i've managed to hold off on the deed but it's still too tempting. I know she won't tell him or nething but if he finds out im sure he wont be too happy about it. I know how women are and they love to gossip and tell everyone their business so im not sure if this is a good idea... any suggestions?