A mum pulled off a hilarious prank on her husband after switching their son for an impostor - and it took him 20 minutes to notice.

Kristy Scott, says her partner often gets engrossed in video games to the point that he is “never aware of what is going on around him”.

To test her theory, she purchased a realistic doll - which she says was made funnier by the fact it looked nothing like their child - and dressed it in her son’s clothes, wrapping it in a blanket and hat to better hide its true identity.

Kristy waits until her husband is fully distracted by the game before asking Desmond to look after their son and placing the doll in his lap.

Without looking down, he takes the fake baby into his arms and continues to stare ahead at the screen as he talks on the headset.

After about 20 minutes Kristy asks Desmond: “Babe, are you still good? Look down at your son.”

As Desmond glances down at their ‘little boy’ for the first time, he’s left stunned before breaking into hysterical laughter at the prank asking and throwing the doll onto a sofa.

The clip has racked up more than one million views on the you tube as one person said Kristy had missed a trick,suggesting: “You should of walked in with your real baby and talked to him while he’s still holding the fake baby.”