Pop star Mel B wrote her rap verse for the Spice Girls' breakout hit Wannabe while sitting on the toilet.

The British singers shot to superstardom after dominating charts worldwide with their debut single back in 1996, and Mel B, aka Scary Spice, admits it didn't take long for her to come up with the rhyme for her part of the track.

"That really annoying rap part, that I love, I wrote in the loo (toilet)," she shared on breakfast show Today. "(It) took me, like, eight minutes to write it...

"Maybe I did a little tinkle (urinated) while I was writing," she smiled, "and then I came up with that (verse) and I was like, 'What do you girls think?' They were like, 'Oh yeah, we like that', so we put that in there."

Mel B will get the chance to relive the popularity of Wannabe on a rumoured reunion tour with bandmates Mel C, Victoria Beckham, Emma Bunton, and Geri Horner, after insisting the big trek is coming, despite repeated denials from fashion designer Beckham.

"I'm the only one (in the group) that keeps on saying, 'We're gonna be performing...'," Mel said, before moaning about Victoria's remarks, "She's always b**ody saying that. Stop it! We ARE touring!"

"Yes, we are going to be doing performances together, for sure," she confidently added.

The girl group, which got together for a top-secret meeting at Horner's home in England in February (18), last joined forces onstage to perform at the closing ceremony for the London Olympics in 2012.