This man was pulled over for driving through a red traffic light. When the policeman checked the man's driver's license, he said, "You're wearing glasses on your ID and you're not now. I'm going to have to give you a ticket."
The guy said, "Officer, I have contacts."
The cop said, "Look mate, I don't care who you know, ... I'm giving you a ticket."
The joke here lies with the meaning of contacts. Contacts is short for contact lenses. To have contacts can also mean to know powerful and influential people. When the man says I have contacts, the policeman thinks he is warning the policeman not to give him a ticket because of his influential and powerful friends.