What happens in Vegas slays in Vegas! That's what Lady Gaga and Ashanti did to the crowd Saturday night when they hopped onstage at Las Vegas' NoMad restaurant to deliver an impromptu performance during jazz trumpeter Brian Newman's "After Dark" lounge show. ET reports that the two divas shared vocal duties on a jazzy cover of Ashanti's 2002 hit "Foolish." Later, Gaga teamed up with Newman for a raucous cover of "Just a Gigolo, I Ain't Got Nobody." Gaga had reportedly performed at her own Vegas residency earlier that night before heading to Newman's show.