What is Grins And Giggles?
1.
For the hell of it, what harm would it do, we might even benefit from it. I believe originated from military-speak.
"For grins and giggles, let's click on this icon and see where it take us."
"Hey, we've got some extra time...why don't you turn down that road for grins and giggles and see where it leaves"
2.
For fun. Can be sarcastic.
"Why are you wearing that awful looking hat?"
"For grins and giggles."
See