thick as thieves
The phrase "thick as thieves" means to have a very close and strong bond or friendship, typically between two people who are involved in some illicit, illegal, or secretive activities. It implies that the individuals trust each other completely, have a deep understanding of each other, and are willing to protect each other even in difficult or dangerous situations.
English is confusing! Why do people say "Pardon my French" when they are speaking English? Because of idioms!
An idiom is a phrase or expression that usually presents a figurative, non-literal meaning attached to the phrase. Does that sound fun? It can be!
Play Just Saying - the word game that makes learning idioms a good time on your mobile phone or tablet.