little brother
kid brother AmE informal

It must have been kind of like going to bed with your kid brother.

For that matter, I know you think of him as a kid brother.

His 30-year-old kid brother did not want to believe him.

So let's talk first about the 7000i's kid brother, the 3000i.

That's a hell of a way to start a kid brother out in life.

Look out for him in the scene where he sees his kid brother's dead body.

"It would be like going to bed with my kid brother," she said.

"I guess he's kind of like a kid brother to me."

The kid brother was so big and awkward that he didn't race as a 2-year-old last season.

She lived with her parents and kid brother in Carson.