There's one piece of the Obama legacy that Vice President Joe Biden is carving out as his own. "I'd like to think I did my part for marriage equality," the vice president said at the Make Progress National Summit on Wednesday in Washington. "And, by the way, it wasn't a half-thought. I said exactly what I believed."

The vice president took youth activists on a long, meandering journey – a speech House Minority Leader Nancy Pelosi referred to as "master class" – in the first of two major addresses he's delivering to progressives this week. Wednesday's speech was at an event sponsored by Generation Progress, the youth arm of the Center for American Progress think tank. The second one will be given at Netroots Nation in Detroit. And while he discussed a variety of issues, it was gay rights where he most marked his territory.

Biden, of course, was bringing up the time he went on "Meet the Press" in May 2012 and endorsed same-sex marriage, beating his boss to the more progressive policy stance. "Because how could I remain silent any longer on this issue," Biden recalled. "And I know the president agreed with me as well." President Barack Obama did, later echoing Biden's statements.

The vice president said the quick turnaround of public opinion on gay rights, which allowed him the political cover, was thanks to the country's youngest activists – including the group he was addressing. "You know, when I meet with progressive groups in the LGBT community they give me credit," Biden said. "I say, 'No, you've liberated more straight guys and women than [I] have.'"

Biden then set a scene. It's 15 years earlier and a group of businesswomen and men are at a restaurant for lunch. "And a waiter with a distinct lisp came up and asked for their order and someone said, 'Well let me tell you what I'd like,'" Biden said, feminizing his voice and pretending to be a restaurant patron picking on the waiter. "Everyone around that table, although they thought it was awful, wouldn't say anything." Because, as Biden put it, this was "appropriate behavior" – the consensus would have been that it's OK to make fun of someone who is gay. (Side note: Biden had a speech impediment as a kid.)

"Imagine what would happen today in any major city in America if some horse's tail said that at a luncheon?" Biden mused. "Everyone else at that table would turn around and say, 'What in the hell are you talking about man?'"

Biden brought up the example not just to tout his record and thank the activists, but to put them to work on another issue: campus sexual assault, something that Sen. Kirsten Gillibrand, D-N.Y., also spoke about at the daylong affair.