The best way to solve this would be to pick three topics ahead of time. If you're worried about the phone's microphone, do so by pen and paper. Then randomly s

The best way to solve this would be to pick three topics ahead of time. If you're worried about the phone's microphone, do so by pen and paper. Then randomly select one of those three topics to discuss on WhatsApp. Finally, keep an objective eye out for ads about all three topics. Ideally, log every single ad you see.