We're not sure what we're most surprised by, here: the fact that Backstreet Boys actually agreed to this, or the fact that their fans paid up to $200 to witness James Corden ruining their night.
With the boyband currently undertaking a residency in Las Vegas, Corden took it upon himself to offer his services and replace one of them for the evening, considering that they had already performed together on his show.
Brian Littrell took the night off so that Corden could enjoy a bit of attention/confused adulation from the audience.
Amusing or cringeworthy? You decide...