Taking the kid places without letting us know.
I suggested the grandparents take the child(3) to get an ice cream just downstairs at our hotel because I thought they would enjoy doing that with him. I was a little hesitant because my MIL(75) has some real deeply ingrained disordered opinions about food, but figured it’d be fine. as they left I specifically said that he didn’t have sunscreen on and to stay out of the sun. 45 minutes later they still aren’t back, so husband calls to find that they have gone to a museum half a mile away without telling us on a 85 F day. No diaper bag, sunscreen, sunglasses, or stroller. No phone call or text. He was fine and so were they, but I was big mad about it and my husband did a tactful rebuke, but who on earth thinks it’s cool to do such a thing?!