The curious laundry incident: God tells Jeremiah to put on, depending on your translation: a linen belt, girdle, waist cloth or loin cloth. Then he tells him to go to the banks of the Euphrates and hide it under a rock. A few days later, he tells him to go and retrieve the garment and, quelle surprise! It's filthy. I cannot tell you how shocked I am that a piece of cloth worn for several days by a person who doesn't know about toilet paper, then left under a rock next to a river for a week would get dirty. Apparently this miracle is a metaphor for what god is planning to do to the Israelites.
How his exact plan is related to the dirty laundry is mysterious: what he's going to do is get them all drunk, then start a fight between fathers and sons. Again, I'm not seeing what's divine about this. I mean, I've seen drunk people come to blows about who was next in line for a bank machine, and although god's name was invoked, I'm pretty sure he didn't have much of a role in it.
All this punishment is coming because the Israelites have been so bad and unfaithful. And then it turns out that one of the most famous lines of the bible is not quite as you remember it, and possibly racist to boot: Can the Ethiopian change his skin, or the leopard his spots? (v. 23) Clearly they were not anticipating Michael Jackson.
There is a drought so bad it's turning donkeys into dragons. So they start praying to god. But Jeremiah is there to tell them that their praying and fasting and sacrificing is having no effect and god is going to kill them with swords, plague and famine. When Jeremiah points out that the prophets have said god promised peace, god vows to unleash the same wrath on them.
God is really going to follow through on his threats this time, and not even the pleas of Moses or Samuel will change his mind. And why is he going to kill his people with swords, famine, enslavement, dogs, beasts and birds? Well, because of something Manasseh the son of Hezekiah king of Judah, for that which he did in Jerusalem (v. 4). I didn't have any idea what Manasseh did either, but Wikipedia reminds me that he reinstituted pagan worship.
More threats: infertility, more widows than sand, young men struck down at noon. The rest will be attacked and enslaved. But all this can be reversed if they just repent!