No flippin' way, buddy.
I took him off to the bathroom, and cleaned him up, and in as calm, and yet friendly-manly tones as possible, explained that this was what happened when you party all night, and that it's cool, this is what guys do...it's our job. Yes, it's stupid, but we can't help it, we're guys...and it's worth it for the partying. He brightened up, seemed to get a certain kick out of this ("insights into the World of Being a Guy") and promptly cheered up.
As we were leaving and up at the counter paying our bill, we were still chatting about it. I mentioned that this feeling was "left over party"...when he seemed confused, I just told him that life was both good times and bad times, but when you party, it's all good times, and that bad stuff just has to pile up and wait it's turn, so the next morning is when that bad part comes out...but it goes away. He liked that idea, but the best part was the waitress behind the counter. Overhearing this convo, and seeing Bug's expression, she leaned forward to Di and whispered "That's very cool; what a great Dad!"
Di mentioned this later on, as I didn't catch it. As I'm sure is obvious, it absolutely made my day.