Fart humor has been a staple of soundboards for years, and motorcycle exhausts that mimic flatulence became a natural spin on the classic fart sound. Riders and editors noticed that a lumpy Harley idle at low revs lines up perfectly with that joke, so short clips like this spread through meme pages and group chats as a ready-made punchline. It sits in the same family as the broader fart meme sound trend, used less for realism and more for the instant, childish laugh it guarantees.