The That's right bro! meme is used after a post whose content is disbeliefed by the community. It's reason is commonly fake messages, grammatical errors, putting something in a wrong place or putting it wrong (a sign marking the entrance – on a blank wall) or just an incomprehensible nonsense ( Google ad: Buy jam four ticket monday bag!) So yes, we actually use it to express deep irony. It has the same meaning as the english slung "YEAH RIGHT BRO". Actually, we don't need to always fill our post with irony, we can also use this meme to approve somebody, something (Facebook: I'm fed up with those teen b***es. Spoiled and failed generation. They are worthless for the humanity -THATS RIGHT BRO). Anyway, this is a rare variant.
The meme itself is a stylized portrait of the well-known Hungarian comedian and actor, Hofi Géza. The origin of the meme is "Szilveszter részegen", a 1991 cabaret. When was it put on the internet and who made the meme is unknown, but it started to spread with the watermark of the Trollfész, a Hungarian fan blog