[XCSme]

I usually don't believe in this stuff and think it's coincidence, but it does happen very often.

One thing that happened in my case, I think I was discussing with someone at a table-tennis club about someone playing squash and he showed me a livestream of that guy playing squash. When I got home I started seeing ads for places to play squash even though I never searched for it on my phone, but this is what I think happened: my phone and his were on the same network, so someone the ad-network associated my device with the "squash" keyword because another device on the same network searched for it.

I think this is usually what happens when you "discuss" with someone, that person or someone else in your proximity might search online for that thing and your device will be indirectly associated with that search.