Slam Poetry is a type of poetry that is performed live and is very close to rap, but without music.The name "slam" comes from the fact that this kind of poetry is competitive. Just like with rappers (as you could see in Eminen's movie 8 Mile), there are slam poetry contests, and Taylor Mali is actually one of the most successful slammers of all time. In the United States, some people use the saying "those who can't do, teach", meaning that teachers are usually professionals who could not find jobs related to what they studied, and are "stuck" with a job that is usually not very well paid. The expression "what do teachers make?" is a pun -- the expression "what do you make" generally means "how much money do you earn", but Mali changes it to express that teachers make students work and think, among other things.
What do you think is more important? the amount of money you earn or the impact your job has in other people? (for ideas, you can check also the comments on the original youtube site for this video)