It’s a sequence of notes that alternates between the fifth and third notes of a major scale, typically starting on the fifth. The rhythm is usually straight 8th-notes, but it may start on the downbeat or on the upbeat in different songs. A singer usually belts these notes with an “Oh” phoneme, often in a “Wa-oh-wa-oh” pattern. And it is in so many pop songs it’s criminal.
Keep in mind that as quickly as these engineered tunes are consumed, they're ‘promptly forgotten.' The love for manufactured music is ephemeral, rarely timeless. Programmatic loops eventually spin into their own obscurity with zero chance at the Lindy effect.