Fold your arms
Definition 1 of 2
Pro Tip 1/3Physical Position
The phrase is sometimes used to describe someone's physical position when feeling relaxed or listening intently. 
During the lecture, many students folded their arms and leaned back.
Pro Tip 2/3Neutral Stance
Not always a sign of negativity; it can indicate neutrality, especially in casual settings. 
The audience folded their arms as they listened to the comedian.
Pro Tip 3/3Observational Gesture
Used as a nondescript gesture when people are observing something without wanting to intervene. 
He folded his arms while watching the street performers.