The grocery store bathroom incident
Took my 3yo into the mens room at Target and he starts yelling DADDY WHY DO YOU HAVE A BUTT HOLE IN YOUR PANTS at the top of his lungs. So apparently he thought my fly was a defect. Everyone within a 50 foot radius heard it. Wife thought it was hilarious when I told her. These are the moments you never forget.
Oh man, this is peak 3yo energy. My oldest did something similar at Costco but with a urinal. The lady next to us was NOT amused. At least he's curious about how the world works, right?