[pests]

I have a friend who this does not work on. In his worse moments he will continue on his phone like nothing happened and not even bring it back up later / forget that we were even talking about something if I were to bring it up later. Super annoying.

[progmetaldev]

I'm not sure if it's this way in your friend's case, but some people will do this on purpose. Usually it is remembered by people that do this intentionally, but sometimes you're just listening and don't want to become part of the conversation. Being put on the spot for people like that is often very negative, and is more likely to get them to forget what was going on, and instead concentrate on how uncomfortable they were made to feel.