Reminder that this is the 'real life' section and you should make a bit more of an effort than make obvious fantasy claims. If you must lie, at least make it a plausible lie.
Anyway, drunken antics notwithstanding, my mother liked going to the beach. In rare cases she would go topless, sometimes for the tan and sometimes for seemingly no reason. I hated when she did that. It was pretty rare though and also, for whatever reason my mother would bring me along despite everyone else being adult women like her. So because it was all women except me, her son, her going topless isn't as unreasonable as it might sound. Where it gets really stupid is when the group had other men aside from me and she, along with some of the other women, did it anyway. Thankfully, all of this was quite rare rather than frequent and as for the other women, some were attractive but I didn't care because I never wanted to be there in the first place.