To wear your heart on your sleeve means to show your feelings openly so that other people can easily see how you feel.
The expression may come from old traditions where people wore a token or symbol on their sleeve to show loyalty or affection. Over time it came to describe openly displaying one's emotions.
The expression may come from old traditions where people wore a token or symbol on their sleeve to show loyalty or affection. Over time it came to describe openly displaying one's emotions.
He tends to wear his heart on his sleeve, so everyone knows when he is upset.