Parent was eating a McFlurry ice cream and gave 5 month old baby a couple of spoonfuls...
YABU - WTF?! He's only 5 months old. His digestive system isn't ready for sugar-rich ice cream! Cue upset tummy and exploding nappy.
YANBU - Get a grip, it's a million degrees at the moment and it was just a couple of spoonfuls. No harm done.