Spotted hyenas "laugh" as a form of communication to relay excitement or frustration. This vocalization can often be heard during a hunt.
To humans, the sounds a frustrated or an excited spotted hyena makes is like a maniacal giggle. To other hyenas, however, this sound is used to let other members of the group know that it has been attacked or that it has made a kill.
Scientists believe the spotted hyena is the only member of the hyena family to emit this sound. Other hyenas have distinct vocalizations used to communicate with their pack, but none laugh like the spotted hyena.
Often, when a spotted hyena makes a kill, other hyenas try to share the bounty. The hyena in possession of the meat doesn't like to share and will "giggle" as a way to tell the other hyenas to back off.