Walked in on my gf getting railed by a bbc. Turns out it was my bully. At first I thought it was a problem, but then she convinced me to watch and help out with whatever she or my bully commands.
Its not that you hated your BFF or wanted them to suffer - but your best friend's sister was so cute and well so was his GF - could you really pass up the chance with both of them? Maybe your best friend will never even know you used their sister and GF