If you're looking for a post related to this, there are several active discussions and memes across different communities:

In a more serious linguistic context, it is considered an idiom where the finger acts as a "fart lever," though some argue it is just a literal request for a prank. Pull My Finger | Cyanide and Happiness Wiki | Fandom

"Pull my finger" is a classic, crude prank where the "joker" asks someone to pull their extended finger, then farts as soon as the person complies. It is often described as a "dad joke" or "grandpa thing" because of its long-standing history as a staple of physical comedy.