Trileros in Barcelona
If you see a group of people and one of them plays with three shakers or shells and a small ball on a cardboard or portable table, DO NOT STOP !.
That person will be asking people to guess where the ball is. Never guess as this is a swindle.
Barcelona is in general a safe town where violent crime is rare, however you should always be aware of pickpockets as they are extremely good.
Tourist are usually the main target so just be extra careful with your belongings as sometimes robberies can be avoided by just being a little bit extra careful.