Signs are a form of Easter egg in the Grand Theft Auto series. They take the form of messages that were deliberately placed by game developers for the players to find, and they are usually ironic or humorous. They have always been hidden in secret and hard to get to places. There is always, at least, one sign in each game that sometimes leads to other Easter eggs.
In GTA Liberty City Stories, the same alleyway sign in Bedford Point is there once again, however, it says different things in the two different console versions of the game. In the PSP version, it says Hello again! with a smiley face on the bottom whereas in the PS2 version, it says You just can't get enough of this alley, can you?. To find out how to get here, the one should see The Hidden Sign.