I'm pretty sure giggle does have childish connotations (it's associated with children), but my question is really; is it so associated with children that it would seem weird to a native speaker if giggle was used to describe an adult's laugh.
Allison giggled, "Definitely. It's very good."
Context: Someone just described a book in a somewhat funny way; there's romantic tension here.
So, does this word-choice feel jarring, considering Allison is a young adult?