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?