One swallow does not make a summer

 Context #1

Jay: I can’t believe mom bought us a trip to Hawaii. Maybe she’ll get us a car too.

Saul: Calm down Jay. One swallow does not make a summer. Remember that mom has money limitations. Let’s not get ahead of ourselves.

Jay: You don’t think mom would do that for us? 

Saul: Be realistic. Just because mom got a new job, doesn’t mean she can afford everything.

Context #2

Peter: I got into college in NY. I’m not worried anymore. I’m sure all the other colleges will accept me too.

Sonia: One swallow does not make a summer buddy. Every school has different standards and rules. Let’s not get too confident about what schools will accept you yet. You should wait before making a decision.

Peter: But this was the most difficult school to get into. How can the other schools not accept me?

Sonia: Sometimes school departments make a difference. It’s not necessarily the entire university that makes that decision. 

Meaning: The expression "one swallow does not make a summer" means that just because one good thing happened, you cannot expect every other thing that will happen to be good. For example, some people think that if something good happens at the beginning of a trip, it’s a sign that everything else will go well. In reality, that is not true. In the first example, Jay thinks that because the mother bought them a trip, surely she will also buy them a car, but there’s no evidence to prove this. It’s just a feeling. In the second example, Peter thinks every college he applied to will accept him because he got into the most difficult one. However, that’s just his belief, not a fact. He is not aware that most universities have differences in acceptance policies and that the standards of each department in that college vary. 

http://languagesystems.edu/

Cut (somebody) some slack

Context #1

Andrew: Last week’s assignment was due two days ago. Why haven’t you finished it yet?

Mia: Andrew, you know I’ve been having some personal problems. Please cut me some slack.

Andrew: There are no exceptions. If I cut you some slack, then everyone will want me to cut some slack for them. 

Mia: You’re so inflexible. I wish you would be more understanding.

Andrew: I would cut you some slack if you didn’t have a habit of turning assignments in late.

Context #2

Jeff: I’ve reported a student for using his phone during class time.

Michelle: Why can’t you cut the student some slack? Maybe the student had a legitimate emergency.

Jeff: He was checking facebook. How would the student benefit from me cutting him some slack?

Michelle: I guess there’s no excuse. You never cut anyone some slack sometimes though?

Jeff: Students get more than enough warnings before being reported. This student doesn’t deserve any slack. He does this daily.

Meaning: The expression "cut somebody some slack" means to give someone permission to do something not normally allowed or to be less strict about something (e.g. a policy or rule). In this example, Mia was upset that Andrew didn’t allow for additional time to finish her assignment. However, Andrew is unwilling to be more flexible because Mia has had a habit of turning things in late. So he is less willing to cut Mia some slack. In the second example, the teacher was upset that the student was focusing on his phone everyday and had been warned about the rules previously. The teacher didn’t think giving the student any more chances (cutting any slack) was of benefit to him or the student.

http://languagesystems.edu/