Britney hasn't always been blonde, but it's definitely her most famous look so we were shocked to see she went brunette!

The singer posted this wacky -- of course -- slideshow of her new look and captioned it, "Same faces, same dress, new hair!!!!! Yes, my sister inspired me to go dark!!!!" We love it!

Meanwhile, Britney's man Sam Asghari sat down with Entertainment Tonight in an interview that aired last night and he talked marriage! "Absolutely,” Asghari responded when asked if he thinks he and Spears, 37 will tie the knot. “This is something that every couple should do. That's the whole point of a relationship -- we are a family."

He went on: "Trust me, if we do ever get married, everybody’s going to know!" It'd be the wedding of the century ... along with Justin and Hailey's, of course!