Oh, I have a seemingly harmless idea so evil, it will ruin the internet forever.
I will make it so every time you open any website, there will be a popup with a question that asks you to invade your privacy, and you can allow it to do so with one click, but you will have to dig through menus if you want to avoid it. Then, after some seconds, another popup will appear, asking you to create a login, no matter what you do. Then, it randomly will ask you to share your location. Yes, with a popup again. Then, just as you thought you're done, another window will open, grabbing your focus, which will demand you talk to a chatbot, and you can't close this one, only slightly minimize it.