I touched her finger with my finger. This seemed to be the correct countermove, but incomplete. So I looked at them without taking my finger away, and waited.
Older one: Now you have to say "true, true."
Me: OK! True, true.
Littler one, satisfied, withdrew her finger.
Older one: You know what YOLO means?
Me: You only live once?
Older one: Yes!
Littler one: It says it on a belt.