When using the word "self" like this:
"My dumb self tripped over the rock,"
would "dumb" and "self" be hyphenated?
No, you would not hyphenate them, as "dumb" is simply an adjective clarifying the noun "self", no different than any other adjective-noun pair (i.e. "a tall mountain" or "a long walk").
The time to hyphenate two words is actually when you are creating a compound adjective by combining two or more words into an adjective. For example, in the phrase I wrote above ("adjective-noun pair"), the words "adjective" and "noun" are combined to create a compound adjective that clarifies the noun "pair". So using your sentence, you would use a hyphen if you wrote something like "my stone-dumb self tripped over the rock".
Hope that helps!
No. You are simply the subject and object of a prepositional phrase, and dumb is an adjective describing the object (self). It is entirely equivalent to:
My expensive cell-phone exploded in my briefcase.
I've hyphenated cell phone for clarity.
