Have you ever spoken to someone, and you can tell how much time they spend on an app? You can hear it in their voice and the phrases they use and reuse. I initially remember this happening when people used Vine. The Infamous "What's 9+10?" and "Damn Daniel" or even "1738" were phrases I heard and said almost everyday when they were popular growing up, as I lived with two brothers and was easily influenced myself. For us, it was a sort of kinship. It was an inside joke that our parents and all elders were outside of, but we could use it to foster relationships with other people of our own age.
Yet, when the Vine app died, this sort of occurrence wasn't as common. That was, of course, until Musically became TikTok, and everyone became obsessed again. Now, a crucial difference between Vine and Tiktok is that in the former, most people created their own videos and individual ones would go viral, or become popular. However, in TikTok, creators are able to use the sounds of other people and explore them in different contexts to explore their meaning and appeal. Because of this, the video itself doesn't need to go viral if the sound is sufficient enough for people to create something new with it. Also, since multiple videos can be created using the exact same sound, one is more likely to hear the same sound multiple times on TikTok even if they are only on it for a few minutes.
When put into this perspective, it is easier to see how people can become used to saying something aloud since they are always hearing it, especially if it is something catchy. This is how people have gone from saying "And I Oop-" to "Me Personally" and "Be F***** For Real". It's how psychological or spiritual terms such as trauma bonding and manifestation have come to be part of ordinary conversation among younger generations. The more time one spend on TikTok, the more they hear particular phrases and subject matters, and the more comfortable they become with discussing them on their own, even if they haven't done any of their own research.