Inventing new words doesn't appear to have worked for Comcast, so they're on to the next tactic: borrowing old ideas.
Setting aside the fact that people opening their mouths and having song lyrics come out is not nearly as hilarious as Comcast thinks it is, we've seen this before. (Warning: the volume on the following ad is much higher than on the Comcast ad.)
Keep in mind: it wasn't funny when Avis did it, either.
One thing Avis didn't do was use a song recorded by a porn star, one that's pretty clearly about sexual activity, and have a mother sing it to her son. Way to gross me the fuck out, Comcast. It's not like they tried very hard to make it fit within the commercial - they even have the son seem confused as to why these particular lyrics make sense in context. So why, exactly, did we think this was a good idea?