Merda

Italian word to describe a person who has behaved badly, usually by betraying the trust of those who were kind to him.

'Sei stato proprio una merda!'
'Sei proprio una merda, ha fatto licenziare Sarah!'

Girare come la merda nei tubi

Typical of the labronic area (Leghorn, Tuscany), means literally "To wander like the shit in the pipes". It is used when you realize to waste your time in doing something or, as well, when you have lot of things to do in different places of the town (offices, market....)

Mi tocca girare come la merda nei tubi per cercare un parcheggio!
(It is very difficult to find a park for my car!)