thigh-slapper vs howler

thigh-slapper and howler both are nouns.

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

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

Other synonyms of thigh-slapper include belly laugh, riot, scream, sidesplitter, wow.

thigh-slapper (noun)	howler (noun)
a joke that seems extremely funny	a glaring blunder
	monkey of tropical South American forests having a loud howling cry
	a joke that seems extremely funny