"As if!" (5)
(Other definitions for not that I've seen before include "Type of logic gate" , "Word of denial" , "A negative word" , "Word of negation" , "logically, operation needed" .)
(Another definition for hah that I've seen is " Expression of surprise (one letter short of a laugh)".)
(Other definitions for pshaw that I've seen before include "Expression of contempt" , "Exclamation of impatience" , "Contemptuous expression" , "scornful reaction" , "Contemptuous cry" .)