thick as thieves
- (idiomatic, simile, of friends or members of a group) Intimate, close-knit.
1884, Mark Twain, chapter 30, in Huckleberry Finn:
- So the king sneaked into the wigwam and took to his bottle for comfort, and before long the duke tackled HIS bottle; and so in about a half an hour they was as thick as thieves again, and the tighter they got the lovinger they got, and went off a-snoring in each other's arms.
1904, Fergus Hume, chapter 9, in The Red Window:
- He and Victoria were as thick as thieves, and are about equal in wickedness.
- 2001 Oct. 26, Tony Karon, "What They're Saying About the War," Time (retrieved 4 Aug 2015):
- President Bush may think he's as thick as thieves with his pal Vladimir Putin, but hopefully someone at the White House is reading the English edition of Pravda.
- Sometimes used with a connotation that the relationship has a suspicious or less than respectable quality.