She's Still Doing it After All of These Years

So, you would think that as your children get older they would eventually stop humiliating you in public. I think I still have a long way to go before that happens. Let me tell you about the most recent encounter. I decided to be nice and wash Tricia's car and also thought it would be nice to relieve her of one of the children. So, Keira and I went through the car wash and then pulled in next to another car at the vacuum stations. I noticed the other driver was an extremely large man and his pants were literally hanging down to his knees showing off his purple boxers. I also noticed that Keira had noticed and, understanding the potential embarrassment this could cause me, I decided to put out this little ember before it became a forest fire. Thinking I was covering all of my bases I said to her, "look, I know you see that man's pants are falling down. Whatever you do, DO NOT say anything about his pants falling down, or the color of his underwear, or about how enormous he is"
Of course she agreed and so we proceeded to vacuum out the car.
As soon as the vacuum turned off Keira yelled to me from the other side of the car, which just happened to be the same side of the car that this gargantuan man with purple underoos was wiping down his car (no vacuum noises there either).
What she yelled: "HEY DAD, IT'S OKAY NOW BECAUSE HE FINALLY PULLED UP HIS PANTS!"
The next words out of my mouth: "Get in the car, we are leaving right now. We will stop later and put the seats back up then so you can buckle up."
My question to other parents out there: On average, what is the age that children don't cause awkward moments for their parents?