Reverse contentfilter, local client(relay?) that requests(receives?) notes from public relays after they have been zapped by friends or friends of friends. Or a zap is the literal notification that a note should be re-stored to the type of relays that lots of people would then choose to use. Make a relay that only stores zapped notes global minus any npub not in the top 10 known irl decent humans and 3 hops of followers, and recommend that relay as a spam and unmentionables free onboarding relay.