They are mainly present in Japanese comics and anime, where they express furiosity, anger or frustration.
Yamete on the internet is mainly paired with cute characters or animals in a wide variety of everyday situations alongside the Japanese saying.
Yamero and Yamete first surfaced in July of 2015 in a thread on the popular image board 4chan. In the /a/ board (which is specifically for anime/manga) a user submitted an image of the anime character Lelouch Lamperouge from the anime series “Code Geass”. Alongside the image was the quote “Yamero” which was the beginning of memes around the Japanese saying.
After its initial surface it took a while for the meme to take on spreading at full pace. In early October of 2016 there was a popular post to the image board Tumblr under the title “Yamero”. Furthermore, to this image there was an audio file of a Japanese Person screaming “Yamero”.
The post gained massive popularity and was saved by over 20.000 people within just over half a year. It was also in October of 2016 where the now popular illustration of the “Yamero Dog” was created by the user adreamcalledeternity. Further spread on Tumblr happened in November of the same year, where another post titled “Yamero” gained huge attention and booked over 150.000 saves globally. All in all after being born on 4chan, the meme was heavily popularized through Tumblr and later on through other boards like Reddit and 9gag.