Simon Cowell has taught his young son to stick his tongue out.

The music mogul and girlfriend Lauren Silverman welcomed Eric into the world on February 14. At just over two-months-old, Simon has already been teaching the tot some cheeky tricks.

Terri Seymour, Simon's ex-girlfriend and still close companion, has gushed about how "gorgeous" Eric is, and how well the star adjusted to fatherhood.

"Simon taught him how to stick his tongue out at two months. It's hysterical - Simon sticks his tongue out and Eric copies, he's so cute!" laughed Terri to Us magazine.

"He's such a happy baby. He wakes up, has his food, and goes straight back to sleep. He's like the dream baby."

Many raised their concerns that eternal bachelor Simon would take time to get used to being a parent. While Terri admits Simon wasn't exactly an expert with babies before Eric's arrival, she believes people's concerns are unfounded.

"He's great actually. I mean he hasn't changed his lifestyle because Simon wouldn't," she mused. "But he's very good. He'd never even held a baby before, so he was like, 'How do you hold a baby?' You have to remind him every now and then about the head... But he's really good and he loves it.

"Everybody was like, 'Oh my God, this is going to be so strange'. It's all been very natural."

And Terri was quick to assure fans that none of 54-year-old Simon's bad behaviour has rubbed off on his young son.

"He's amazing, he's the most well-behaved baby... considering he's Simon's! He never cries. I literally heard him cry once," she smiled.