Is it normal that it drives me nuts when my sister in law brings her random ppl

So my husbands little sister usually calls before she pops round but makes no mention that she's bringing some random with her?! It drives me nuts!! It's Sunday n I'm trying to do the house work n get everything ready for my sons school bags for tomorrow, so I'm dressed but haven't done hair or make up, basically I'm not in stranger mode!! On my doorstep is my sister in law n some tarted up little girl, they bring their own drinks n go outside in my garden to have a cigarette with my husband! I think I already know this shouldn't annoy me as much as it does but GRRR!!!