(Following a very upset ride in the car away from her house, and in hysterical tears)
"Hi. Oh no, I forgot to give you a high five. And that is why I am crying so much. I am sad I didn't give you a high five when we said good bye. Boo hoo."
Grandma Becky had a good idea to do a high five on the phone by tapping hand in the phone. This helped ease DHH's anxiety and he stopped crying so hard.