John Oliver Slams 'Bully' Trump, Geraldo Rivera's Mustache and a 'Crazy' French Politician (Video)

The "Last Week Tonight" host also blasted Fox News for their glee over the President's Syrian bombing and took specific aim at Geraldo Rivera, who said, "One of my favorite things in the 16 years I've been here at Fox News is watching bombs drop on bad guys."

Take a look at the highlights of the HBO late-night show below.

Oliver decimated the President for his flip-flopping on foreign affairs, considering Trump tweeted while President Obama was in office that the United States should "stay out of Syria."

"The President seems to change his mind based on any information that is new to him, which seems to be almost any information," Oliver said. "And that is genuinely worrying. We have a leader operating on a learner's permit, and we were reminded just this week of what our President has at his disposal."

Oliver then tackled the fact that the President was initially noncommittal about his responsibility in deciding to bomb Syria when he released a statement that said, "Everybody knows exactly what happened, so ... and what I do is I authorize my military. We have the greatest military in the world, and they've done a job -- as usual. So, we have given them total authorization."

"What the f--k was that?" Oliver asked. "That was a 'yes' or 'no' question to which you vomited 38 words -- none of which were 'yes' or 'no,' although to be fair, none of them were 'Holocaust center' either, so I guess we should be partially relieved."

"If you have a bully in the White House, he does violent, impulsive things that seem to be inching us closer to —- among other things —- potential nuclear war with North Korea," Oliver concluded on the subject. "And if that happens, it's gonna take a f--king amazing piece of chocolate cake to help us forget about it."

Oliver eviscerated Rivera's "Fox & Friends" appearance after he praised the dropping of "bombs on bad guys."

"Oh, that's a coincidence, because one of my favorite things in four seasons on this show is getting to look directly into the camera and say, 'F--k you, Geraldo. I hope your mustache gets caught in a box fan," Oliver said.

Rivera explained his position on on Friday's "Fox & Friends" by saying, "It's not gonna win the war, but it certainly sends a message. You know, I had a bully in high school. A guy named Richie. You never knew what Richie was gonna do. He had a temper. Sometimes he'd want to kill ya and sometimes he'd let ya go."

"I like that they think Donald Trump is like Richie from my high school," Rivera added. "I want the bad guys to think that he could do anything to them at any moment, and I think that that has a positive impact."

Oliver strongly disagreed.

"Holy shit! You see, this is why bullying never works. If you have a bully in school, there is a good chance he's turning some kid into the next Geraldo Rivera. And if you have a bully in the White House, he does violent, impulsive things that seem to be inching us closer to, among other things, potential nuclear war with North Korea."

Rivera on Monday fired back at Oliver via Twitter and said, "To John Oliver. MOAB killed 90+ ISIS. Remember them? Baby killing terrorists, throat cutting savages who rape and burn religious minorities?"

During the longest "Last Week Tonight" segment (above), Oliver had a grim warning to issue to France while highlighting the importance of the European country's upcoming election.

The comedian said candidate Marine Le Pen, who is head of the right-wing National Front, "is the main reason you should be invested in this election."

Le Pen -- much like President Trump -- is anti-immigration and unapologetic about her stance. Oliver quoted her as saying that immigrants would like nothing more than to come into your home, brutalize your wife, steal your wallet and take your wallpaper.

"Hold on," Oliver said. "Brutalizing your wife and stealing your wallet, again, that's just boilerplate racism. But 'people are coming to take my wallpaper' is something a crazy person says. No one wants your wallpaper, you catastrophically weird person."