sidesplitter vs thigh-slapper

sidesplitter and thigh-slapper both are nouns.

Word	Noun	Adjective	Verb	Adverb
sidesplitter	Yes	No	No	No
thigh-slapper	Yes	No	No	No

As nouns, sidesplitter and thigh-slapper are synonyms defined as:

Other synonyms of sidesplitter include belly laugh, howler, riot, scream, wow.

sidesplitter (noun)	thigh-slapper (noun)
a joke that seems extremely funny	a joke that seems extremely funny