あいつは口が軽いからこのことは言わない方がいい。
Don't tell him. He's got a loose tongue.

家では赤味がかった髪とそばかすのせいで、母が侮蔑を込めて 「にんじん」と名付け、皆にもそう呼ばせています。
At home, because of his reddish hair and freckles, his mother scornfully named him "carrot" and had everybody else call him that.