Boris Johnson and Co. start dumping raw sewage into rivers and the sea.

They're posting every MP who voted in favor of it on Twitter. Some of the posts are simply unbelievable. There's one I saw (and lost as it refreshed) where they had several newspaper clippings over the last few years in one area of Britain that stated something like:

Leaving the EU will roll back our Environmental Protections

which was followed by a response article headline:

Completely Unfounded Fear Mongering by the Left

which was followed by the headline a few days ago:

14 BEACHES YOU CAN NOT SWIM AT DUE TO POLLUTION