The 'What in Tarnation' meme features an image of a Shiba Inu dog wearing a tiny straw cowboy hat, looking confused or bewildered. The phrase 'tarnation' is a 19th-century American slang euphemism for 'damnation,' used here to express extreme shock or disbelief. The meme first gained traction on Tumblr and Reddit around 2017, quickly evolving into a wordplay trend where the suffix '-ation' is replaced to fit various contexts, such as 'what in tarnation' becoming 'what in hydration' when the dog is near water. It remains a staple of internet culture for expressing mild outrage or confusion in a humorous, Southern-styled way.