The pig's "hehe" sound is a maternal behavior and an instinct to protect its young. One reason is the secretion of hormones, such as progesterone and estrogen. This can also explain why this maternal behavior is very strong during pregnancy and childbirth. When someone approaches the sow, the sound of "hehe" is just one of the more common manifestations.
Ha ha, another interpretation:
The word "hehe" is a kind of provocation, which means that there is something wrong with your world view, and scolding you is lazier than scolding you. This is the subtext of hehe, and there is no over-interpretation.
Hehe, it belongs to cold violence, and its purpose is to make others feel their disgust. Just like the word ghostly was originally used to describe calligraphy, now it means monster, so we naturally regard it as a monster. Many people say hehe means happy, but seven or eight out of ten people think hehe is unfriendly.