A bonus child noun phrase slang
Used to refer to the child born by your husband or wife from a previous marriage.
His classmates bullied him for being a bonus child when his mom got married again.
He always feels inferior to his siblings because he is a bonus child.
He hates being a bonus child when his mom got married to another man.
It is never easy for him to be a bonus child in a totally new home.
To reorganize your own circumstances
You failed the exam twice because you were lazy, you have to get your shit together if you want to graduate.