wear one's heart on one's sleeve - to show one's feelings clearly and openly by one's behavior; to be an open book.
Origin:
From the old custom in which a young man tied to his sleeve a favour — perhaps a ribbon or handkerchief — given to him by a lady as a sign of her affection (i.e. of her heart). The expression is now used of one's own heart (i.e. feelings) on one's own sleeve.
Example:
You can't help but see how he feels about her; he wears his heart on his sleeve.
John has always worn his heart on his sleeve, so there's no doubt who he'll be supporting.
get shirty (with smb.) - become angry with someone.
Example:
Don't get shirty with me! I'm only reporting the new rules.
have smth. up one's sleeve - to have secret plans or ideas; to have a secret or surprise plan or solution (to a problem).
It alludes to cheating at cards by having a card hidden in one's sleeve.
Examples:
I've got something up my sleeve, and it should solve all your problems. I'll tell you what it is after I'm elected.
If I know her she'll have a couple of tricks up her sleeve.
We've been negotiating my new pay and conditions, but I've kept the other job offer up my sleeve for the time being.
off the cuff - improvised; spontaneous; without preparation or rehearsal.
An off-the-cuff remark is one that is not planned (always before noun).
Examples:
Speaking off the cuff I'd say the scheme is doomed to failure.
He made several off-the-cuff remarks which he later denied.
Her remarks were off-the-cuff, but very sensible.
A: The professor called on me today to give a presentation.
B: Really? Were you prepared?
A: No, I had to deliver the presentation off the cuff. I don’t want to have to do that again.
give (smb.) the boot - to get rid of somebody; to fire someone, to force someone to leave a place.
Example:
They gave him the boot for swearing at his manager.
She gave him the boot because he wouldn't stop talking about his ex-girlfriends.
tighten one's belt - to spend less money.
Examples:
Things are beginning to cost more and more. It looks like we'll all have to tighten our belts.
Times are hard, and prices are high. I can tighten my belt for only so long.
buckle down (to) - to apply oneself with determination; to begin to work seriously at something.
Examples:
You had better buckle down and get busy.
All right, we'll buckle down now and study for exams.
They chatted idly for a few moments then each buckled down to work.
Jim was fooling instead of studying; so his father told him to buckle down.
Originating about 1700 as buckle to, the expression gained currency with the football song “Buckle-Down, Winsocki” (from the Broadway musical comedy Best Foot Forward, 1941).