chortle
verb (used without object)
to chuckle gleefully.
Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
So every one had been chortling through several scenes before the significance of their laughter occurred to them.
From The Phantom Herd by B. M. Bower