age of consent
The age at which a person is legally able to give consent, as to sexual relations, marriage, or a binding contract. Some people advocate lowering the age of consent, but some worry it will cause an increase in promiscuity among young people.
silence means consent
If you do not voice your objection to something, then it is assumed that you support it. A: "Why did you think I would agree to punishing a student so harshly?" B: "Well, you didn't say anything when we originally discussed this plan! Silence means consent." Make sure to speak up when you disagree with something, because, for many people, silence means consent.