Answer:

haha

Answer	Crossword Clue
HAHA	Laugher's syllables
HAHA	Response to a joke
HAHA	Response to a one-liner

HAHA	"Very funny!"
HAHA	That's a laugh
HAHA	Chuckling sounds
HAHA	Gag reflex?
HAHA	Nelson's catchphrase
HAHA	Some laughs
HAHA	Sarcastic laugh
HAHA	Chuckle

HAHA	LOL relative
HAHA	Sarcastic chuckle
HAHA	Sunken property divider
HAHA	"Good one!"
HAHA	Funny modifier?
HAHA	Landscaper's turfed trench
HAHA	"Told you so" response
HAHA	Laughing syllables

HAHA	"That's a riot"
HAHA	"The joke's on you"
HAHA	"Very funny"
HAHA	Pun response
HAHA	Sarcastic response to a joke
HAHA	"That was a joke?"
HAHA	"Very funny--not!"
HAHA	"That's a riot ... NOT!"

HAHA	Laughter syllables
HAHA	"That's funny!"
HAHA	Sounds of mirth
HAHA	"Aren't you the comedian?!"
HAHA	Bit of mirth
HAHA	Oft-sarcastic utterance
HAHA	"Funny ... not!"
HAHA	"I get it, but ..."

HAHA	Gag response
HAHA	Crack reaction
HAHA	Facetious "Not funny"
HAHA	Often sarcastic joke response
HAHA	Sarcastic joke response