(a) blank cheque
If you give someone a blank cheque, you authorise them to do what they think is best in a difficult situation.
"Tom was given a blank cheque and told to negotiate the best deal possible."
(a) wet blanket
To refer to someone as a wet blanket means that they spoil other people's fun, or make an event less enjoyable than it could have been.
"Come on Mike! Don't be such a wet blanket. You're spoiling the party!"
(a) blessing in disguise
A blessing in disguise refers to something that is unpleasant at first but later turns out to have advantages.
"Missing the plane was a blessing in disguise - that's how he met his wife. She was a member of the crew on the next flight!"
(a) blind alley
If you go up a blind alley, you follow an ineffective course of action which leads nowhere, or produces no results.
"The suspect's 'revelations' lead the police up a blind alley."
(as) blind as a bat
Someone whose vision is very poor, or who is unable to see anything, is (as) blind as a bat.
"Without his glasses, the old man is as blind as a bat."
(the) blind leading the blind
The expression 'the blind leading the blind' describes a person with very little ability trying to help or guide a person with no ability.
"Don't ask Sofia to translate it. She hardly speaks a word of English herself. It would be a case of the blind leading the blind."
blind someone with science
If someone tries to blind you with science, they confuse you with their knowledge by using difficult or technical words.
"When you ask Tim for a simple explanation, he blinds you with science."
(in the) blink of an eye
If something happens in the blink of an eye, it happens nearly instantaneously, with hardly enough time to notice it.
"The pickpocket disappeared in the blink of an eye."
on the blink
If a machine is on the blink, a light flickering on and off shows that it is not working properly and needs servicing or repair.
"What a nuisance! The photocopier is on the blink again."
blockbuster
Something that is outstanding, impressive or particularly successful, such as a film or a book ,is called a blockbuster.
"The TV series was a blockbuster."
makes your blood boil
If something makes your blood boil, it makes you really angry.
"His condescending attitude made my blood boil!"
makes your blood run cold
If something makes your blood run cold, it shocks or scares you a lot.
"The look in the prisoner's eyes made my blood run cold."
(get) blood out of a stone
The expression 'get blood from a stone' refers to something that is very difficult to obtain.
"Negotiating a reduction from that company is like getting blood from a stone!"
blood, sweat and tears
A project or action which involves blood, sweat and tears requires a lot of effort and hard work.
"His success wasn't due to luck; it was blood, sweat and tears all the way."
a late bloomer
To refer to someone as a late bloomer means that they take longer than usual or expected to develop in a particular field, show their talents or demonstrate their capabilities.
"He was quite slow at school but he turned out to be a late bloomer who is now a renowned academic ! "
blot one's copy-book
Someone who blots their copy-book does something to spoil their good record or reputation.
"He blotted his copy-book when he was arrested for speeding."
blow away the cobwebs
If something blows away the cobwebs, it makes you feel more lively and refreshes your ideas.
"Let's get out of the house. A walk on the beach will blow away the cobwebs!"