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/

To shoot from the hip

Context #1

Dana: Karen, I need to buy a new shirt for my company dinner tomorrow night. I think I'm going to buy one of these two. What do you think? Which one?

Karen: Well, the red one with the yellow sleeves is interesting - and bright. It really catches the eye! But the white and blue shirt will probably look better with your skirt. I'm just not sure I like the pink buttons. Hmmm, I don't know. Let's ask Roger.

Dana: Roger, what do you think of these two shirts? Which one would you buy if you were me?

Roger: Neither. They are both ugly.

Karen: Wow. He really shoots from the hip.

Context #2

Dear Professor Andersen,

I wanted to write you to ask if our group could submit our project again. Joseph and I did a lot of research and planning. Fred, on the other hand, did very little work. Fred knew this, so he promised Joseph and I he would read and organize all of our work and put it all together. I guess he decided to shoot from the hip because none of our research was included - and he didn't do any. Joseph and I are very worried about our grade.

Thank you for your consideration,

Jane

Meaning: To say or do something without thinking carefully about it. This can be used in a positive or negative way. When this idiom is used, it can mean a person is direct and honest (positive) or careless and thoughtless (negative).

http://languagesystems.edu/