Admitting to something directly can feel less fun than denying it while the evidence says otherwise. The not me doing caption format leans fully into that playful contradiction.
What this caption format actually does
This self-aware caption structure playfully denies an obvious action while actually documenting and admitting to it in the very same post, using mock denial for comedic effect rather than any genuine attempt to actually deny what's happening.
The humor lives in the contradiction
The comedy here comes specifically from the contradiction itself — denying something while the accompanying photo or video evidence directly proves otherwise, creating a playful, knowing wink to whoever's reading the caption.
What kinds of actions get this treatment
This caption format commonly applies to minor, slightly embarrassing, or relatable actions — an impulsive purchase, a guilty pleasure, or a small habit someone is sharing with a knowing, self-deprecating tone rather than genuine embarrassment. 
A black and white cat with a mustache is looking at the camera with a caption that says... — view on SoundGIFs
Self-deprecating rather than genuinely embarrassed
This format works best for things that are only mildly embarrassing, letting someone poke fun at their own minor habit or slip-up without it feeling like a genuinely uncomfortable confession.
Part of a broader family of confession memes
This format belongs to a wider family of memes built around knowingly admitting something while performing mock denial, all relying on the audience immediately recognizing the playful contradiction rather than taking the denial literally.
Similar self-aware caption structures
This format sits alongside other knowing, self-aware meme structures, similar in spirit to how what does girl math mean uses obviously flawed logic on purpose, fully aware of the humor in admitting to it.
Conclusion
The not me doing caption format turns a small confession into a playful, self-aware joke rather than genuine embarrassment. For more meme formats and internet slang explained clearly, browse SoundGIFs' full News section.