final though-tag: That tongue at the end tho; That victory dance though

For the last few years the internet has abounded with expressions ending in a kinda of "though-tag" in final position, especially in comments to GIFs and the like, such as the following:

That tongue at the end tho. (imgur)

That victory dance though. (imgur)

I'd very much appreciate it if somebody, problably a native speaker, could add an explanation with some synonyms.

----------EDIT-----------------------

The pics in imgur are no longer titled as they were when this post was created.

In standard usage, sentence-final "though" (optionally preceded by a comma) is used where the current sentence or phrase qualifies or limits what was said earlier. E.g., it might point out a flaw or drawback, or conversely a silver lining or mitigating circumstance.

• He's handsome. Kinda dumb though.
• It's beautiful. Real expensive though.
• Forrest Gump wasn't very smart, but he was honest though.

This is slightly informal, more common in speech than in writing. Note that it cannot be substituted with "although" in this context.

The usage you noted, which does not involve any prior sentence and is often written with "dat" and "tho" or even "doe", seems to be a modern Internet meme usage.

The website Know Your Meme discusses the "dat X tho" meme and credits one particular viral Vine from 2013 for popularizing it. See the link, the dialog is:

• [Purse snatcher grabs a girl's purse and runs off with it]
• "Help, my purse!"
• "I'll save you!"
• [Would-be savior performs a useless stunt instead of helping to catch the thief] "Woo hoo!"
• "He's already gone."
• "Yeah but that backflip tho."

The fact that he skillfully executed a backflip is humorously presented as a mitigating circumstance for criticism that he failed to act to stop the crime.

Urban Dictionary has an entry for "dat ass doe" (i.e., "that ass though"), expressing the thought that if a girl has a pleasing posterior it mitigates the fact that her face may not be so pretty or her intellect substandard. In other words, there is an implied and unspoken earlier phrase.

However in practice, I think "tho" is sometimes simply added gratuitously to the end of a "dat" phrase and then its usage morphs to be just an emphatic particle. Perhaps like sentence-final Canadian "eh?", except without the rising tone.

Sorry for the above example, but Urban Dictionary didn't have another less sexist "dat" phrase to cite. Know Your Meme mentions that "dat ass" itself probably originated on the 4chan website circa 2009.

The use of "though" at the end of the sentence can differ. It can carry the meaning of contradiction (~"however"). From bbc.co.uk:

We use though and however when we want to add a comment that seems to contradict or contrasts with what has already been said.

"I’m sorry, I can’t stay for lunch. I’ll have a coffee, though".

However, in your example, the usage does not carry any significant connotation, it is a sort of slang usage that might put some extra emotional emphasis on the subject. The definition from Urban Dictionary is more to the point:

To add more unecessary words to a sentence....though is not really used for much when coming at the end of an already complete sentence.