Make sure the post is 'square' to the floor. [=make sure that there is a right angle where the post and the floor meet]
I'll go on the trip if I can 'square it with' my parents. [=if my parents will agree to let me go]
Here's the rest of the money. Now we're 'square'. [=now we don't owe each other anything]
(..) our king, is he has to carry that responsibility, and it's very heavy. So, it slows him down, and he can only move one square at a time. Mafia. What are you doing here? I've got a present for you. Found it in our house. I thought you might want it. (..)2014 The Dark Horse
(..) lowlifes and degenerates out on the street and you sell your little pussy for nothing... for some lowlife pimp who stands in a hole? I'm square? You're the one that's square, man. I don't screw and f$ck with a bunch of killers and junkies the way you do. You call that being hip? (..)1976 Taxi Driver
(..) You're a young girl. You should be home now. You should be dressed up, going out with boys, going to school. - You know, that kind of stuff. - God, are you square. Hey, I'm not square. You're the one that's square. You're full of shit, man. What are you talking about? (..)1976 Taxi Driver