Dad-to-be Keith Urban is learning a lot about fatherhood, including a few new words. Urban and wife Nicole Kidman have been inundated with baby gifts for their first child, due next month. The problem is, Urban is unfamiliar with some of them.

"We got a tie-dyed jumpsuit thing that we really like," he said backstage at the CMA Music Festival in Nashville, after making a surprise guest performance. When a helpful reporter told him it was a 'onesie', the perplexed Urban replied, "A what?" Then he laughed and explained, "I'm learning a new vocabulary." He also told reporters that one of his favorite gifts was a tiny, Johnny Cash-inspired T-shirt that reads "I crawl the line."

Urban is enjoying having his pregnant wife on the road with him, at least for the time being. "I love having her with me when I tour, but at the same time, it's work. You don't want to ask too much of your family," he explained.

The Urbans know the sex of the baby but are keeping it a surprise for friends and fans. This will be the couple's first child. Kidman has two adopted children, Isabella and Connor Cruise, with ex-husband Tom Cruise.