What a funny fence! (2-2)
I believe the answer is:
ha-ha
I believe this is a double definition.
'what a funny' is the first definition.
'fence' is the second definition.
(I have seen 'Sunken fence' mean 'ha-ha' so perhaps 'fence' could also mean 'ha-ha')
(Other definitions for ha-ha that I've seen before include "Sunk fence" , "Sunken boundary wall" , "Sunken barrier" , "Sound of laughter" , "Ditch with wall in it - sounds merry" .)