sniggers

Sniggers is the plural noun and third-person singular verb form of snigger, a half-suppressed or stifled laugh, typically one that suggests mockery, disrespect, or awareness of something inappropriate.

To snigger is to laugh in this manner: The students sniggered at the teacher's mispronunciation.

The word is more common in British English; American English tends to prefer the variant snicker, which carries identical meaning.