thick as thieves

Meaning

1. (as) thick as thieves

   very friendly, especially in a way that makes other people suspicious

In the movies · 3

• Yeah. Thick as thieves, those two.The Life of David Gale2003
• Y'all two, thick as thieves. Give me that.Moonlight2016
• And they all thick as thieves.The Best of Enemies2019

From the same entry

• give a thick ear
• thick as two short planks
• a thick head
• your thick head
• a thick skin
• blood is thicker than water
• thick on the ground
• in the thick of
• through thick and thin
• lay it on thick
• thick and fast