bigm:
No, my mother didn't need a reason to laugh - she just used to burst out laughing spontaneously!
My earliest recollection was when we were kids and she took my brother and I on one of those "mystery tours" (usually ending up at the seaside!), during the school hols.(couldn't afford a "proper" holiday).
So, we're all looking out of the window of the double decker bus we were on when mother simply began to guffaw, tears streaming down her face. The bus was rocking long before we got anywhere near the seaside !!!