All of a sudden was a favorite phrase of mine, and it still is. As someone who feels like everything in life is happening all at once, it works. All of a sudden, my pen ran out of ink. All of a sudden, the ducks were in the road. All of a sudden, my fake mustache peeled off and fell into my coffee with a fuzzy plorp.
Everything is a surprise with all of a sudden. An unexpected delight (or not).
It turns out we've been using "of a sudden" since Shakespeare first coined it in The Taming of the Shrew. "Is it possible That love should of a sodaine take hold? (antiquated spelling alert!) Sudden has been used as an adjective since the 15th century, and it was once a noun, too, meaning "that which is sudden." Today the noun form is obsolete, except in the phrase "all of a sudden."
What a gem!
All of a sudden, the word sudden is no longer a noun.
All of a sudden, thanks to Mom, a memory, and the internet, I know a little more.