wear (your) heart on (your) sleeve

to make your feelings and opinions obvious to other people.

John's always worn his heart on his sleeve, so there's no doubt who he'll be supporting.

• a prima donna
• a prime mover
• a priori
• a prophet of doom
• a pub crawl
• a put-up job
• a Pyrrhic victory
• a quantum leap
• a queer fish
• a question mark over something
• a queue-jumper
• a quick fix
• a quick one
• a quick study
• a quid pro quo
• a race against the clock
• a race against time
• a race against time clock
• a rainy day fund
• a rake-off
• a rap across the knuckles
• a rap on the knuckles
• a rap over the knuckles
• a rap sheet
• a rat fink