Is-leveling, in some nonstandard dialects of English, is the use of the word "is" in places where standard English has "are" occurring. For example: "We is brothers."
This usage was widely stigmatised as being a solecism but now may go unnoticed in speech when the "is" is abbreviated, for example; the statement "There's some birds" would likely garner no correction.
Was-leveling is the use of the word "was" in places where standard English has "were."
Were-leveling is the use of "were" where standard English has "was" leading to sentences like: