I read a sentence which was:
They do it on the daily.
Consider the part "on the daily". Daily is a noun as it is preceded by a preposition. But most of the dictionaries define "daily" as a noun as either a newspaper or any servant. So, how do you interpret this?
On the daily and on the regular are both slang phrases that mean on a regular basis. This English StackExchange discussion dives into on the regular a bit, and someone mentions on the daily in the comments. Both slang phrases seem to originate largely from hip-hop culture (or at least that seems to be their vector into the mainstream). Another example, from the Black-Eyed Peas' "My Humps":
I drive these brothers crazy,
I do it on the daily.
It is not "standard" English to use an adjective as a noun, so this phrase should not be used in formal written English and should probably be avoided by most learners, but native speakers have certainly encountered slang uses of adjectives in the place of nouns in other situations (e.g., "I have a sad!" - incorrect, but very common on the internet).
