It's a newer type of phrase/way to start a sentence. It's kind of like a way to call attention to or put extra emphasis on the action taking place.

For example, say I got to an ice cream store and try 10 flavors. I could say "not me trying every flavor before getting a single scoop."

It kinda adds a sarcastic or lightheated feel to the sentence.

It's a variant of the sarcastic "that couldn't be me"

e.g.: "Goofing off for a week and then cramming the night before the final exam? That couldn't be me /s." -> "Not me goofing off for a week and then cramming the night before"

They put their watches in "wrestling mode" then their parents get notified of when they stopped "wrestling"

Not is the correct word.

It’s a typo.

Should be “now”

Tell me you're old and out of touch without telling me you're old and out of touch.