not put (something) past (one)
1. To believe one is capable of doing something unsavory, immoral, illicit, selfish, etc. He's a very charming guy, but I wouldn't put it past him to stab me in the back if it meant advancing his career. I should know by now not to put such vile treachery past the likes of him.
2. To be unable to swindle, fool, or deceive one. My grandmother might be 85, but you still can't put a thing past her! That sleazy used car salesman couldn't put his bogus little scam past me.
put (something) past (someone)
To believe that someone is incapable or unwilling to engage in some sort of extreme behavior or action. Usually used in negative constructions. A: "Do you think Joe stole the money?" B: "Honestly, I wouldn't put it past him. He has no conscience." You're more naïve than I thought if you would put unauthorized spying on private citizens past the government.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
To believe some action, especially an extreme action, to be of a kind that someone would not do. Often used negatively: I wouldn't put it past those kids to try to climb to the top of the flagpole. Would you put murder past these thugs?
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.