Suffixes are word parts added to the end of a word to change its meaning or grammatical function. "Funny" is a base word on its own.
Let's compare it to some words that *do* have suffixes:
* Funnier: This word has the suffix "-er" added to "funny," making it a comparative adjective.
* Funniest: This word has the suffix "-est" added to "funny," making it a superlative adjective.
* Funnily: This word has the suffix "-ly" added to "funny," making it an adverb.
So, while "funny" can be used as a base to create new words with suffixes, the word itself does not have a suffix.