what does "pfft" in chat language mean?

From Chat Lingo:

Pffft is distaste, or sarcastic. 
Feh is similar to pfffft. 
http://irc1.singnet.com.sg/c_lingo.htm


The term "pfft" is not so much an acronym as onomatopoeia. An
Onomatopoeia is a word that imitates the sound it represents.

It implies dismissal or lack of interest.

From the Urban Dictionary:

- An expression of dismissal of another's comment

- An expression of disgust, disdain or disapproval, usually uttered
after someone has just told you something totally inane or
uninteresting.

- An expression of a lack of interest in another persons comment

- Fine, whatever, I don?t care

Urban Dictionary
http://www.urbandictionary.com/define.php?term=pfft&defid=1150022


According to the  Glossary of Gaming Terms n' Acronyms, pff/pfft is an
 expression of dismissal.
http://www.cubeowner.com/forums/lofiversion/index.php/t3182.html


From the DMusic Forum

?the "pfft" Sian was making was a visual representation of a sorta
raspberry/fart-like sound one might make in a sorta purposeful
childish way to denote that you don't like something but aren't being
wholeheartedly serious on the matter at the same time.?
http://bluestraveler.dmusic.com/forum/1752




Search terms used: 
Pfft means
Definition pfft

I hope this helps!

Best regards,
Bobbie7

Just a thought, but the urban dictionairy isnt necesarily the best
place to source from.

What's wrong with the urban dictionary?  This is my first exposure to
it.  The word, being onomotopeia, is closer to slang than formal
English.  I would expect the Urban Dictionary to have better
definitions of slang than just about anything.  What something means
from someone who says it can be different than what some stuffy, old
book says.

Look around more in the urban dictionairy... its more of a joke than anything else