How do you use the phrase "as ... as can be"?

I know you can say " happy as can be," but can you us any adjective before "as can be"?

Can I say " I was as American as can be"? or " He was as excited as can be"?

Many adjectives can precede "as can be". Some are used far more frequently than others, including "happy".

Here's a list of the top 20 adjectives that typically come before the expression:

(Courtesy of CORPUS OF CONTEMPORARY AMERICAN ENGLISH)

You can only use the construction with classifying, absolute and extreme adjectives if you're being tongue-in-cheek or whimsical.

*/?'The bridge is as wooden as can be.'

*/?'The weapon is as nuclear as can be.'

*/?'The event is as annual as can be.'

*/?'He was as dead as could be.'

*/?'It is as microscopic as can be.'

But often non-gradable adjectives are treated as gradable with secondary senses:

as American / alive / full as can be.