Sentence Mixing is a very diverse and popular element in YouTube Poops. It involves manipulating already said sentences from a source and using them to create new words and phrases (i.e., someone says 'fire truck' and it is edited to make the word 'fuck'.) It is continuously increasing in popularity due to its highly comedic effect when done well.
It's widely seen mostly in CDi-oriented poops, as seen in Sentence Mixing is for Pussies by cjflo. Other sources can be edited as well, such as advertising campaigns by Billy Mays, political debates, and much more.