Commonly used in YouTube Poops, Sentence Mixing is the act of taking voice clips from a TV show, song, or movie and putting the clips together to make your sample say something that they didn't/wouldn't say.
Robotnik: My PINGAS is going in that pesky Hedgehog's BUTThole!
Person: Wow, this creator is great at Sentence Mixing!
The S shape that everyone drew in school.
Person1: Dude remember the Cool S?
Person2: Yeah that was so cool! I'm gonna try drawing it.