It is an idiom, first used by William Shakespeare in Othello: "But I will wear my heart upon my sleeveFor daws to peck at: I am not what I am. " (Act I, Scene I, said by Iago)
display ones feelings openly, usually with respect to matters of love newdiv ntembu says this was the result of a computer glytch - another answer posted
I think the phrase is commonly attributed to Shakespeare from his play Othello, in a line spoken by Iago: "I will wear my heart upon my sleeve" [1.1.65]. Of course, Iago's intent was to deceive...
It is a common expression, and means to let your emotions be on show to others. Many people have used such an expression, doubtless including many Shakespearean actors. Although the concept and...