After exhanging emails and texts you finally meet the guy only to discover he is not as attractive as one would hope...and in actual fact has a face which resembles a boot AKA Bootface.
1. (n.) The face one makes when they exclaim, "Boom!".
2. (interj.) Exactly like exclaiming "Boom!" This works because it conjures the mental image of the face you would have made had you just said, "Boom!" (Note: typically is performed without actually making a boomface.)