Poll: The tickler's face

When you're watching tickling videos where you can see the tickler's face, what sort of expression do you like to see on their faces as they tickle their victim?
Do you like to see them laughing and having fun? An evil smirk as they make their victim suffer? Stone cold and focused on the task at hand? Anything else?
My personal preference is the happy smile, where the ler is smiling and laughing almost as much as the lee.
Let me know, I am very curious.