What is similies words of

A clown is as funny as a

Similes compare two things. Because clowns are considered by most to be very funny, the object would also have to be something funny.

Therefore you could say ...

A clown is as funny as a medieval joker.

A clown is as funny as a cat barking like a dog.

A clown is as funny as a comedy movie.

A similes for that is A clown is as funny as my sister falling

or a clown is a funny as a dog barking you really have no wrong answer with that