You can't argue with a wise 4yo

I'm struggling to get Child #4 dressed for a playtime session in one hour. He keeps asking me to button his pants for him, but I won't because he isn't wearing underpants! I insist that he go upstairs and put his underpants on. He replies, "But no one can see under this!" as he pats his pants. Okay, so no one will be able to see that he isn't wearing underpants, but I know and that is enough! I actually won this argument... it is a sign that I will have a good day!