Answer:

pfft

Answer	Crossword Clue
PFFT	Fizzing-out sound
PFFT	"Yeah, whatever!"
PFFT	Dismissive sound

PFFT	Fizzling sound
PFFT	Dying-out sound
PFFT	Sputtering sound
PFFT	Up-in-smoke sound
PFFT	Fizzling-out sound
PFFT	Fizzling-out sound effect
PFFT	"All gone"
PFFT	Sound of something going kaput

PFFT	Sound of a fizzling firecracker
PFFT	"All gone!"
PFFT	Ending sound
PFFT	Sound of a flop
PFFT	"All gone!" sound
PFFT	Up in smoke
PFFT	Kaput sound
PFFT	Fizzling out sound

PFFT	Sound of disappearance
PFFT	Fizzled-out firecracker sound
PFFT	Go ... (fizzle)
PFFT	[Fizzle]
PFFT	Kaput
PFFT	[fizzle]
PFFT	Indication of a dud
PFFT	"That's nuthin'!"

PFFT	Dud's sound
PFFT	How a dud goes
PFFT	Scoffer's sound
PFFT	Go .. (fizzle)
PFFT	"Just like that" noise
PFFT	Sound of dismissiveness
PFFT	[scoff]
PFFT	[Just ... disappeared!]

PFFT	Sound of failure
PFFT	Sound of a dud