hang loose

relax, be at ease; wait patiently; take it easy (Informal)

The "shaka" sign is a common greeting gesture. It is often associated with  Hawaii and boarding sports such as surfing, skateboarding and snowboarding. It consists of extending the thumb and pinky finger while keeping the three middle fingers curled, and raising the hand as in salutation. Sometimes the hand is rotated back and forth to emphasize the sign. It is also sometimes referred to as an E-E-E.
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be calm, relax, do not be uptight In Hawaii, they tell the tourists to hang loose - to relax.

idm. ใจเย็นๆ, สงบใจเอาไว้ slang. สงบสติไว้, ใจเย็นๆ (syn. stay loose)