The girl's mum had given her a box filled with clues about a "big surprise".
As she picked up and looked through the baby toys, pink babygros and scan photos, she still had no idea what was going on.
"Why would we give you baby clothes?" her mum, who was filming her reaction, asks.
"I don't know, my baby clothes?" the girl answers, still completely unaware.
The mum doesn't push her for an answer and instead, leaves her pondering while looking at the baby scan photo.
After a few seconds she asks: "Are you having a baby?"
Her mum nods and tells her she's going to have a baby sister.
The girl looks at her in shock and breaks down in tears, not knowing what to say.
"Is this something you've wanted for a really long time?" asks her mum, who by this time is in tears too.
And the young girl nods - completely speechless - while wiping the tears away from her face. Aww.