a. in swearing, cursing, etc
b. downright disgust
but is also used as
a. a harmless expletive or
b. as an expression of surprise or admiration
2. Word origin
Possibly, amfufu is a product of the creative evolution of the phrase "anak ng puta" (son of a bitch).. "anak ng puta" became "amputa"... online game chat filtering of words resulted to creative modification and creation of new words to bypass the word filtering.. and amfufu is one of those created words.
(Online game chat, after superior player A killed low-level player B while player B is levelling up)
Player B: Amfufu ka! Noob lang kaya mo! (Son of a bitch! Noob-killer! Pick somebody your own level!
Player A: LOL! Noob!
2.a harmless expletive / as an expression of surprise or admiration
(Online game chat,after one player A showed off his upgraded weapon to player B)
Player B : Amfufu! Ang ganda ng sword mo! (Holy shit! Great sword!)
Player A : :)