Alright. So I took a photograph of the back of two milk cartons. It has the same 4 box style of the ones I showed my adult class. So here is my take on them with my limited Japanese (and especially the local dialect). You might need to click on the picture to see them.

Let's start with the one on the left. It appears the gran has a sore stomach in the first panel. I think the grandson has suggested she drink some delicious hot milk... obviously. Mmm mmm delicious Kochi milk. Wait a second? What's happened to her? Her skirt has blown off and she's about to wet herself? The grandson looks excited by this. Maybe he spiked her milk? The comic concludes with the grandfather waking up to find the bed wet. "Not again!" he says. Deary deary me. This story escalated very quickly from delicious milk to the reality of old age and its accompanying ailments.

Translation: The gran complains that recently she has been sleeping bad. The grandson then mentions that before going to sleep you should drink hotto miruku. I think he means hot milk. Then she replies with some gibberish about sitting. The grandson is excited because there's hot something and then hot underpants! I have no idea what shes says next so I looked it up. She's says "This is effective! or something. It is still uncertain at this point whether she has actually wet herself... that would be an effective way to get hot underwear. I think I was correct. Alright... the grandpa is pretty pleased with the hot underwear. Maybe he likes it. I think the punchline is that he can now sleep because the bedroom atmosphere/mood has become pleasant. Excellent stuff.

I'm so happy that we have a second comic to analysis and breakdown. Especially since the local dialect just throws about letters all over the place. Grandpa looks pretty pleased in the first panel. I think he's sleeping better because the wife is wetting herself. Maybe he has taken it upon himself to try this new milk creation himself and see what all the fuss is about. The grandson appears to be showing him how to drink. I think the Americans introduced it after the war so maybe he isn't aware of it yet. This is Kochi prefecture after all. We have a picture of a cow next. I guess the grandson is showing him where the milk comes from. He asks... what part of the cow is it? Do you squeeze the juices out the head? The head is always the most derishasu. Then the grandson laughs and proclaims "No! We squeeze it out the cow's nipples of course! That's completely natural!". I am suddenly disgusted with milk.

Translation: Alright the grandpa is giving some praise rubbish about the milk and cows being mostly local to Kochi or something. The kid is giving it some oishii. You should know that since I taught you it. Then he talks about two things involving the ground that I don't know. I have no idea what the picture of the cow is talking about. I think it mentions a four panel comic and something else about Kochi cows? The text on the udder says MILK BANZAI! which is just a celebratory cheer I guess. The punchline is a bit weak. I think オチチis meant to mean udder/breast and オチ actually means the punchline of the joke.