Play a social game on Facebook - any of the ones that grant you additional advantages for inviting your friends. (In other words, 100% of the successful ones.) There's so many obviously fake, for-games-only accounts loaded up with completely unconnected for-games-only 'friends'.

When Facebook gets serious about deleting these accounts - irritating the platform's developers and impacting the money it makes through Facebook Credits - then I'll believe their real-name-only approach is non-negotiable.