If someone wears their heart on their sleeve, they behave in a way that makes their feelings very obvious, for example when they are in love with someone.
PHRASE
藏有…想法;留有锦囊妙计;心中另有…高招
If you have something up your sleeve, you have an idea or plan which you have not told anyone about. You can also say that someone has an ace, card, or trick up their sleeve .