In the context of a blind date, an escape hatch is a pre-arranged call placed by a friend to your cell phone shortly after the start time of the date. If the date is going well, the call can be ignored. If the date is a nightmare so far, you answer, pretend that the caller is informing you of an emergency that requires your presence, then excuse yourself immediately. This allows you to cut the date short without embarrassing either party. The phrase can also refer to the friend who places the call.
You: Hey, I have a date with that guy from nerve.com at 8:00; can you be my escape hatch?
Friend: You want me to call you at 8:30 or 9:00?
Prior to the apparent adoption of the word by chavs, a "random" was a slang term used to refer to a person who was clearly and obviously out of place in a particular milieu and whose presence was therefore questioned. Usually a neutral to negative connotation.
A: Who was that guy in the glasses and tweed jacket who showed up at our sorority meeting?
B: Clearly some random.
Some random dressed in a clown suit just ran across the quad mooning people.