1/ They can't be taught to be "teams" because there is only one team.
2/ The rhyme is "machines".
3/ He didn't teach them how to be teens, he taught them how to be ninja teens. It's harder than it sounds. You can't just be a ninja and a teen and say you're done. You have to learn to be a teen ninja or you will just end up being a jerk with ninja weapons.
4/ I had a cupcake with coconut frosting for breakfast. It was yummy.
5/ Ryan North linked to the youtube
6/ That bastion of hyper-correctness, Wikipedia, has this line: The lyrics were also changed, such as changing "Splinter taught them to be ninja teens" to the "Splinter taught them to be ni-fighting teens." This happened due to an error in the lyric changing. That's from a discussion about the way it was exported to certain countries who didn't like the word Ninja. I hope this blog entry is not banned from those countries. I have it on good authority that coconut cupcakes are not banned in those very same countries.
7/ The TMNT wiki itself which definitely didn't copy Wikipedia no siree bob, has a similar line: The lyrics were also changed, such as changing "Splinter taught them to be ninja teens" to "Splinter taught them to be fighting teens.".
8/ Ninja ninja ninja ninja.