He told MTV News: "I actually did karaoke with Rob. That's random, isn't it? We were on our way to Japan, and he was promoting ['Twilight'] and I didn't talk to him at all on the flight, because he's this really tall guy with a hood over his head literally, and every time I'd go to the bathroom, I'd be like, 'Man, that guy takes some serious sleeping pills,' because this was him slumped over the whole time.
"He sang very well. I can't even remember what it was he was singing. Man, he's got a voice. Really soulful."
Although he was impressed with Robert's vocals, Hugh admitted the whole experience was a "little weird".
He explained: "The first thing you do is you get inside this room, the doors are closed, and there's, like, eight of you. So it feels a little weird. And then all of a sudden, they open, and they bring in these boxes, which are basically [full of] dress-up [clothes], and it's all girls' clothes. I was a schoolgirl, Baz got dressed up, and Rob did not. He was too cool for school."