You have a teenage son. Recently he's started hanging out with a group of friends who are rough and like to get in trouble. You think that he's recently started smoking because of these friends. You think to yourself:
They're a bad influence on him.
friend (topic), influence, teenagers 
Your teenage son has been hanging out with a group of older guys who you don't like: they're rude, lazy, and like to start fights with people. You tell your son:
I don't like you running around with that crowd.
You live in a small town. You're talking to your teenage nephew, who lives in the same small town. He says he wants to move somewhere else as soon as possible. You can understand why he wants to do that, so you say:
I don't blame you.
agreement, decision, set phrase, teenagers, town 
You're talking to a friend about your teenage son. In the past few months, your son has been starting to listen to loud and aggressive music. He wears dark clothes and acts angry a lot. But you're not too worried because you think it's normal for his age. You tell your friend:
He's going through a little rebellious phase.
When someone's behavior changes for a few years, you say that they are "going through a ___ phase".
To understand "phases", you can think of the moon. Sometimes the moon is full, sometimes it's half full, and sometimes it's completely dark. But you don't worry when the moon is dark because you know that it's a normal and natural event which will change again soon. We call the moon's appearance at different times "phases".
In the same way, people naturally change as they get older. When children are between 3 and 4, they enter an "inquisitive phase" (a time when they like to ask a lot of questions). Most kids between 11 and 14 go through an "awkward phase" in which they don't seem comfortable because they're not children anymore but not yet teenagers either. And a lot of people between age 15 and 25 go through a "wild phase" when they like to drink, party, and date lots of different people.
If you say that someone is "going through a phase", it sounds like you think that they will soon stop acting the way that they're acting:
Don't worry about it. He's just going through a phase. He'll grow out of it.
People call things "little" that they don't respect very much. For example, if someone who you go to school with threw a party but didn't invite you, you might angrily say:
I guess I wasn't invited to her little party.
Here's an example from a previous PhraseMix lesson:
Teenagers often try to do the opposite of what their parents want. This is called "being rebellious".
Your teenage son is listening to music on his earphones with the volume really high. You can hear it from across the room. You want him to turn the music down because you're worried it will hurt his ears. You tell him:
You could cause permanent damage to your ears, you know.
You and a friend saw a teenage couple making out on the street. You don't think they should do that. You say to your friend:
That kind of behavior is not appropriate in public.
You're outside on the street with a friend and you see a teenage couple kissing. You don't think it's proper for them to do that in front of strangers, so you say to your friend:
Can you believe these kids just making out on the street?
disapproval, gossip, public, slang, teenagers You're giving advice to your son, who's getting bad grades in school. You want to tell him how to be more successful in his studies. You say:
It's all about self-discipline.
advice, children (talking to), studying, teenagers Your 14-year-old son took your car and drove it around. He was caught by the police. When you go to pick him up at the police station, you're angry and scared because it was such a dangerous thing for him to do. You say:
You could have killed someone!
Your 14-year-old son took your car and was driving around the town. He got caught by the police. When you go to pick him up at the police station, you're extremely angry. You say:
What the hell were you thinking?
