"You know ah...sis...."  He trailed off even as he approached her.  His arm was thrown around her shoulders and he'd keep his pace slow to match hers.  "But I've seen girls walk like that before.  I mean...you could have told me you were getting it on with someone around here.  I would have kept to myself and everything.  I don't want to ruin your game and all.  If you want me to go somewhere I can."  Brian was blushing.  To think, his sister had SEX!