suss out

From suspect.

suss out (third-person singular simple present susses out, present participle sussing out, simple past and past participle sussed out)

1. (slang, transitive) To come to understand (a person).

   We've sussed him out — he only drinks on Fridays and only in that bar in town.

   • 2019 March 19, Mike McKee, “The Case of the Missing Data”, in Dark Reading‎:

     In essence, security experts most familiar with this breach believe that a nation-state — likely China or Russia — stole the data in order to suss out current spies and pick out potential targets they could recruit as spies.

2. (slang, transitive) To manage to work (something) out, to determine (something).

   We've sussed out how to open the lock.

   • 2012 April 20, “Electric cars: Difference Engine: Tailpipe truths”, in The Economist‎:

     As far as electric cars are concerned, motorists have sussed out that they do not make particularly good financial sense, even with a $7,500 handout from the federal government.