"Be like" usage

Of late, I have been noticing a lot of casual memes floating around, particularly on Facebook, that involve this phrase. Typical constructs could be like the following examples:

B*&^%$# be like...I need a break.

Niner fans be like...but we won five times!

Liberals be like...I hate guns.

I understand these are strictly informal constructs. But I'd need a native speaker's (American English because most such memes seem to originate in the US) take on:

1. how casual these phrases are, i.e. if they can be used in semi-formal fiction writing?
2. how this usage originate and if it has any affiliation to a particular dialect group, e.g. Midwest, African-American, Southern American, etc.

There are two, maybe three, different things going on here:

• Habitual be, as John Lawler and J_LV observe, is characteristic of AAVE; it now appears to be spreading from that dialect into the speech of ‘Millennials’, and I am informed by my 24-year-old son that the use is not entirely ironic: it is marked as non-standard but employed unselfconsciously. For instance, the common catchphrase Haters gonna hate may be paraphrased Haters be hatin.

• ‘Quotative’ BE like, with a finite form of BE representing a singular event, is another matter. In the 1950s the very old dialect use of like as a ‘discourse marker’, with only a very remote sense of similitude, experienced a sudden upsurge among the ‘Beats’, and indeed became a conventional sign in the representation of the speech of jazzmen and their followers. By early sixties it had been widely adopted among white teenagers across the US (I cannot say when it gained currency in other speech communities), and it was about that time that I first remember encountering ‘quotative’ BE like.

  Since then BE like (and bare like) has been in continual use. It is particularly associated in popular imagination with the speech of teenagers, particularly the Southern California dialect called Valspeak, but in fact it is not restricted to any region or sociolect: I hear it every day in casual use by people of every origin and every calling.

  It is true, however, as J_LV says, that it is strictly a casual usage. It is not used in writing except where dialogue is represented; in fact, it would have no point in writing, since its characteristic use is to represent what follows not merely as a quotation of someone’s words but as a representation, a mimesis, of that speaker’s performance. And in speech it is still more characteristic of teenage than adult speech, because as people grow older they achieve a firmer grasp of formal speech and avoid casual use when there is any sense that it may be inappropriate.

• The utterances you quote marry these two senses: be is employed as a finite verb signifying habitual or generic application and like to mark what follows as a representation of behavior. The answer from teenager Farooz Masroor confirms that this is employed across ethnicities to “mock a certain stereotype of any group of people”.

There is also (my son patiently explained to me) another be like usage which marries both of these: X be like Y employs a mimesis of X’s just-occurred singular performance of Y to express that that Y is characteristic of X. “Watt be like doodly-whomp!” for instance states that J.J. Watt’s brutal sack of the quarterback is the sort of thing he does all the time. This may also be expressed as “Watt be all doodly-whomp!” —But this is only for immediate responses; with past events, the verb reverts to ordinary finite form.

Teenager here!

Be like is used to mock a certain stereotype of any group of people, mocking what they say or do by posing it as their opinion. Eg. Teachers be like 'have this homework over the break.'

It's only encountered in casual speech between teenagers (or at least not between students and teachers). You could use it in fiction writing if it's in a quote, eg. "'Teachers be like 'have this homework over the break,'' said Bob." But you cant say, "Professor McCarthy was like 'have this homework over the break'" (unless your story is narrated by such a teenager who feels the need to speak casually and you feel the need to stay in character). I have no information about its origins but at this point nearly every ethnicity can be found to use it sometimes in casual speech. I have also seen "N***as be like, blabla" sometimes when talking about a black person, or if the speaker is a black person.

Edit: Turns out that I myself made a facebook post a while ago using 'be like.' Context: last year as a freshman I had a challenging history teacher who loved to put strange compare and contrast questions on his tests. My post reads, " be like 'To what extend is Adam Smith's capitalism inherently Machiavellian as it relates to the historical trajectory of Yuan dynasty China?'"

It's the "invariant be" - see section 3.1.2 of this paper.

Walt Wolfram contends that usage of the invariant be is age-related, in that young people cease to use it as they grow older. The earliest reference in that paper is a survey of non-standard English by the US Department of Education in 1968 (Labov et al. 1968).

However, that's almost certainly not the first use of the invariant be, but rather when linguistics researchers started to see value in describing African American Vernacular English (AAVE). I suspect that origins of a lot of AAVE, including the invariant be, is irrevocably lost.

The meaning is really interesting, because this is not a simple case of subject-verb disagreement. According to this paper, the invariant be functions as present simple tense in which recurrence is explicitly indicated. Taking an example from the question, "Women be shopping" indicates that women habitually shop, similar to "women shop", except that the habit is explicitly indicated by be.

The present continuous "Women are shopping" indicates that a group of women are currently shopping, i.e. not the same meaning as "Women be shopping".

Based on my reading about AAVE, I would say the archaic usage is unrelated. In archaic usage, "be" is the dynamic verb (e.g. "there be vermin") of the present simple tense, whereas invariant be is a static verb in the AAVE usage.