It’s somewhat surprising that until now, John Oliver and Last Week Tonight have not done a deep dive on impeachment. It’s the kind of complicated bureaucratic process that Last Week Tonight has made its bread and butter—and unlike pennies or psychics, there’s already a genuine public interest in the topic. That might be why on Sunday, he told relatively few jokes—instead taking a straightforward approach as he explained how impeachment works, then made the case for impeaching Donald Trump. Oliver seemed to know that he had a captive audience for this subject with or without humor, and that in this case, the argument itself could and should be the star of the segment.

“Ever since this president got elected, people have been dying to see him impeached,” Oliver said, adding that 63 House Democrats now support an impeachment inquiry. But some Democratic leaders, including Nancy Pelosi, have been resistant. The House Speaker recently argued that impeachment does not mean what most people think it means—that it does not immediately remove a president from office. Or, in Pelosi’s words: “[a]ll you do, vote to impeach, bye bye, birdie.” Oliver conceded that Pelosi was right—but he couldn’t help but ding her for her references.

“Nancy Pelosi knows there’s simply no better way to connect with the average working joe than by referencing a Broadway musical from 1960,” Oliver quipped. “Also, if this situation were to be a musical, it wouldn’t be *Bye Bye Birdie. It would obviously be Grease, where a rapey guy with weird hair treats women like shit and yet somehow gets everything he’s ever wanted.”

The basic impeachment process begins with an inquiry in which a committee within the House investigates and holds hearings; if a majority decides they’ve found impeachable offenses, they vote to impeach. From there, the Senate holds a trial, and if a two-thirds majority votes for removal, only then will the president actually be removed from office. The basic point, as anyone who lived through the Bill Clinton impeachment proceedings well knows, is that impeachment does not guarantee that a president will be booted. As Oliver points out, no president has actually been removed by the impeachment process; Clinton and Johnson were both impeached but remained in office, while Richard Nixon resigned before the House could finish impeaching him—“sort of like an Irish goodbye, if Nixon didn’t also hate the Irish.” Plus, removing Trump would require 20 Republican senators to vote for such an outcome—which seems unlikely to happen.