On HEL-NGO the other day, everyone in J cabin was given a small (A7?) leaflet with headline "become silver in one trip". No discrimination, even platinums were offered this fast track
The promotion said: Sign up for AY+ today, get 5000 points free and possibly get silver status. The "details" were cryptic, something like "Today's flight might also fast track you to silver", but no mentions of the exact rules.