Miranda Lambert buys Carrie Underwood a motorbike

Country star Miranda Lambert surprised pal Carrie Underwood over the weekend (24-25May14) by handing her the keys to a brand new motorcycle.

Former American Idol winner Underwood took to her Twitter.com blog on Sunday (25May14) to share her delight at the unexpected gift and posted a photo of herself posing on the black and chrome bike.

In the accompanying caption, the star wrote, "Well, it's not every day @mirandalambert buys you a motorcycle!"

However, Underwood revealed she would need a little training before hitting the road with her new toy, adding, "Next stop, motorcycle driving lessons!!!"

Lambert has yet to reveal the reason for her generosity, although the bike was delivered a week after the pals shared the stage at the Billboard Music Awards in Las Vegas on 18 May (14) to perform the TV debut of their new song, Somethin' Bad.