Ha ha. Of course, it's the plural of humf.
It sounds like someone is choking.
So you mean that humfs is two people choking?
But, according to google, it's also this:
Stockholms Universitet
(HumF)If you are looking at Swedish university life, HumF stands for Humanistiska f?reningen (The Humanities Faculty Club) at Stockholm University. Founded in 1914, it is a student-run organization that hosts social events, book clubs, pub nights, and provides study spaces at the "Gula villan" campus building. You can read more about their current activities on the official HumF Student Association Page
HA! HA!