AEST 10:00, Fri Jan 31 2014
This little boy isn't too happy about getting another baby sister.
With two sisters already, Gunnar was less than pleased as he cut into a pink cake, revealing the gender of his new sibling.
While sisters Paisley and Harper were pretty happy about the new baby, watch as their brother throws a mighty temper tantrum.
Click through to watch some more good, bad and hilarious big siblings, including a boy's awesome reaction to being a big brother and some naughty big sisters.
Boy doesn't want a baby sister