General synonyms:
* Funny
* Amusing
* Comical
* Witty
* Jocular
* Droll
* Facetious
* Satirical
Synonyms emphasizing specific aspects of humor:
* Lighthearted: suggesting playful or carefree humor.
* Wry: dry or understated humor.
* Sardonic: harsh or cynical humor.
* Ironical: humor based on the incongruity between what is said and what is meant.
The best synonym will depend on the context of your sentence.