As the title above, why do japanese locals remove theいfrom the いadjective when speaking. For example, I have heard words like 早、やば、高 being used when speaking. Is this only used amongst friends (very casual), or can it also be used in formal situations?
I know that removing the い from the adjective and appending a さ turns the adjective into a noun. But if さ is not appended, will it stay as a verb, rather then bring turned into a noun?