Following his viral takedown of Donald Trump [1] in February, John Oliver is back at it again — this time, he's focusing on Trump's famous Mexico wall plan [2].

"It's one of the few policy proposals Trump has talked about in detail, so instead of mocking it, let's take it seriously," he says. That means disecting how practical it actually is.

First, Oliver shows clips of Trump saying the wall will cost $4 billion — and then clips of him contradicting himself saying it will cost up to $12 billion. After noting that Trump plans to make it out of concrete, rebar, steel, Oliver cites experts who say this plan will end up costing upwards of $25 million.

"It's a big, dumb, thing that only gets more expensive over time," he jokes. "It's like getting a pet walrus — you think it stupid now, wait until you learn what a bucket of sea cucumbers cost. You're not prepared for that."

Watch the full clip and then check out why Trump and his plans will never make it to the presidency. [3]