卖关子 To sell the key point. To hold back the crucial part on purpose and keep others waiting for it.
通风报信 To let the wind through and report the news. To pass one side’s secrets to the other side in secret.
小道消息 News from the side road. News that does not come through official channels and is often unreliable.
看家本领 The skill that guards the house. A skill in which a person is especially strong. The dictionary’s example says: “This is his house-guarding skill. No one else can learn it.”