When I'm not doing anything else I tend to grab the skin just above my collarbone on my neck and pull on it because it's pretty elastic and will stretch far.
I also pop the joints of tons of things on my body. My bottom and middle knuckles on both hands (both knuckles on my thumb), my wrists, my toes, my elbows, my neck, my back, one shoulder (or both if both need it but usually only one does), the joint that connects the base of the inside of my hand to my wrist, and sometimes my knees or various other joints in my feet/other areas.
Edit: Another thing I do is scratch the bridge of my nose if I'm on the verge of tears. Idk why I do it, maybe to distract myself, but I always find myself doing it when I feel tears coming on.