Coordinate adjectives require a comma in between, for example:
- That's a big, red house.
But it looks odd to write "big, old" or "big, ol'," for example:
- That's a big, ol' house.
Rather, it's looks more right without the comma, for example:
- That's a big ol' house.
Google Ngram seems to back that up much of the time:
"...used to be a spring and a big old fig tree."
"He and his five sons would hitch a horse up to a big old rock..."
"Look for...the big old oak tree."
Ngran : "big old"
So why does "big old" so often not appear with a comma in between? Is it grammatically incorrect to write "big" and "old" without a comma in between? Or is there some special rule that applies to "big old" and/or "big ol' " that allows the exclusion of the comma?