Cold water on the face
Run the tap as cold as it goes. Fill your hands, hold your breath, and put your face in the water. Eyes and cheeks matter most. Hold for fifteen to thirty seconds. Repeat two or three times.
No sink nearby: a cold wet cloth, or a cold can, across your eyes and cheekbones.
If you have a heart condition, skip this one.
Why this works
Cold water on the face sets off a reflex every mammal has: the body prepares for a dive and slows the heart. That part is reliable. Evidence: solid Whether a slower heart makes the anger or panic easier to carry is less tested, but early results point that way. Evidence: decent