American Pie star Jason Biggs and Jenny Mollen are expecting their second baby

American Pie's Jason Biggs and his wife Jenny Mollen have announced the wonderful news that they are expecting their second baby together.

The couple took to social media to tell fans and friends that they are growing their brood from a family of three to four.

Jenny, who is a best selling author and actress, posted a sweet but funny announcement on her Instagram page.

The 37-year-old shared an image with her 178k followers of the loved-up couple sitting in bed wearing matching black tops. Hilariously the pair had placed a 'snot sucker' plastic tube in between them, each holding one end with their mouths.

With Jenny looking at the camera, and Jason pulling a funny buzz-eyed face, the scene looks a little confusing until you read the humorous caption.

Jenny wrote of breaking the news of a sibling on the way to her son, 'This is how I told my son babies are made. #numbertwo #nosefrida @fridababy #teetsreincarnated'

Fans went wild for the announcement, with many commenting on the picture with messages of congratulations and support.

One Instagram user wrote, 'Awwwww, so happy for you all!!! Congrats!' whilst another added, 'wait this is your pregnancy announcement? 😂'.

Some social media users seemed to relate to the idea of explaining the baby making process to your little ones, with one comment reading, 'when you need to explain the birds and the bees to G2 😂😂😂'

Another fan shared their own experience with trying for a baby, 'I hope your fertility rubs off on me...been trying for baby #2 for months 📆'.

The pair, who starred together in the comedy series I Like You Just the Way I Am already share a three-year-old son Sid.

Jason has previously spoken out about life as a father saying, 'That change that happens is so tangible. It happens overnight, and it's the craziest thing.'