Nick Lachey's son has entered the terrible twos.

The 40-year-old singer, who previously claimed his 22-month-old little boy, Camden, was ''an angel,'' admits he recently started displaying some naughty behaviour.

The VH1 host, who announced this week that his wife, Vanessa Lachey, is pregnant with a baby girl, told ''He knows the word 'no' - of course he didn't learn it from me, but he knows the word.

''He's a typical 2-year-old. He sees how much he can get away with and pushes the end of the envelope, but it's a lot of fun.''

The former 98 Degrees singer thinks Camden is very entertaining.

He said: ''It's a great age. He's discovering his personality, he's getting into everything [and] he's talking like crazy. They start to figure things out and push their boundaries.''

Shortly before confirming he and Vanessa are expecting their second child, Nick admitted he was eager to have a daughter.

He said: ''We won't wait too much longer. I really want to have a little girl.''

The couple, who started dating shortly after Nick's split from ex-wife Jessica Simpson, tied the knot in 2011.