The 52-year-actor dropped by The Ellen DeGeneres Show, airing Thursday, and admitted that last weekend's celebration -- which also included 23-year-old Patrick Schwarzenegger -- got pretty epic.
"There was lots of love, lots of pride, lots of happiness, lots of Visine," Lowe jokes. "There might have been some vomiting. There might have been one of the guests meeting a young lady and getting their wallet stolen ... I'm just saying, it's Las Vegas."
Still, the father of two is proud he was able to keep a handle on things.
"Here's the way I look at it -- nobody got arrested, nobody ended up in the paper," he notes. "Everybody is healthy, so I'm claiming victory and getting off the field."
Lowe -- who's legendary for his own headline-making exploits in his younger years -- also talked about his own 21st celebration, which he spent with his infamous crew, the Brat Pack. The superstar '80s group included Demi Moore, Molly Ringwald, Andrew McCarthy, Emilio Estevez, Ally Sheedy, Judd Nelson, and Anthony Michael Hall.
"My 21st birthday I was rolling with the Brat Pack, that was the height of my posse," he shares. "And everybody made me a surprise party."
But the only way they could get him to the location was lying to him and telling him he had a blind date with Madonna.
"And I was like, yeah,'" he hilariously recalls. And of course I got there, and it's a surprise party, and it's really great, but then the whole night I was just bummed because Madonna wasn't there. 'Guess I'm not gonna hook up with Madonna tonight' ..."