there's just someting about having to protect the lil sis...i don't have one and could care less who she fucked if i did have one but most people don't think like me....but whatever you do, if you DO get with her dont' fuck her over....cuz you will surely have your ass handed to you then....assuming your friend could whoop your ass.....and btw there is no way you are going to keep it from him....just no way in fuckin hell unless you plan on never calling her (if she's a teen you can drop that whole idea right off the bat) and you only see her in school and your friend goes toa diffrent one for some reason...basicly there is no way to hide it. becareful you are treading on very thin ice with this whole thing