John Oliver attempted to provide his viewers with a better understanding of GOP’s Obamacare replacement plan Sunday night, breaking down why it’s great for Paul Ryan’s “erection,” but terrible for poor Americans.

Oliver’s position is based on two elements of the proposed American Health Care Act: 1.) The switch from Obamacare’s insurance tax credits to flat-tax credits based on age 2.) The destruction of Medicaid.

“It gets rid of Obamacare’s insurance tax credits, which are based on many factors including income, and replaced that with a flat-tax credit based on age,” the "Last Week Tonight" host said. “The older you get, the more money you get. That’s easy to understand. Think of it as the exact opposite of being a woman in Hollywood.”

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So how does the flat-tax credit help struggling Americans compared to Obama’s Affordable Care Act?

“Let’s say you live in Woodward County, Oklahoma, you’re 60 years old, and you earn $50,000 a year,” Oliver said. “Under Obamacare you’d get $13,350 toward insurance, but under the new bill that will drop down to just $4,000. That is over two-thirds less.”

“That is really just one example. There are a lot of people who will be harmed by this switch to flat-tax credits,” he said. “And experts say one thing is pretty clear here: Those who are lower income would be particularly hurt — and that is before we even get into Medicaid, the program that largely provides healthcare to poor and disabled Americans, because that is where this bill gets really vicious.”

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And also the part of the bill that gets Ryan “rock hard,” according to Oliver.

“You know the changes to Medicaid are rough just from how creepily enthusiastic Paul Ryan sounds talking about them,” Oliver said before playing a clip of the Republican Speaker of the House promoting the bill on the radio. “He is rock hard talking about that. Somehow you can actually hear his erection in that. And if you don’t know what he’s talking about, that just sounds like a benign pile of words, but when he says ‘defederalizing,’ ‘block granting’ and ‘capping,’ what that means in laymen’s terms is cutting the living shit out of Medicaid.

Oliver pointed to an analysis saying that the plan would cut at least $370 billion in federal funding for Medicaid over the next 10 years, putting the burden on states to make up for that loss of federal funding, which the comedian asserted would be “next to impossible” for many states.

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“Millions of the poorest Americans will lose coverage," Oliver said. "And I literally just heard Ryan getting another erection when I said those words. And when you combine that with the insufficient tax credit, an estimated 6-15 million people are projected to lose insurance.”

Oliver then turned to CNN, which reported the top 1 percent of American income earners would receive a $33,000 tax break from the bill, while the top 0.1 percent would receive an average tax cut of $197,000.

“This plan is literally taking money from the poor and giving it to the very rich," Oliver said.

Watch the entire "Last Week Tonight" segment in the video above. 0311_trump_casting_insetView PhotosGettyCasting Inevitable Donald Trump Election Movie