N  inexpectation, non-expectation, false expectation, miscalculation, surprise, sudden burst, thunderclap, blow, shock, start, bolt out of the blue, wonder, eye opener, unpleasant surprise, pleasant surprise, nonexpectant, surprised, unwarned, unaware, off one's guard, inattentive, unexpected, unanticipated, unpredicted, unlooked for, unforeseen, unhoped for, dropped from the clouds, beyond expectation, contrary to expectation, against expectation, against all expectation, out of one's reckoning, unheard of, startling, surprising, sudden, unpredictable, unforeseeable (unknowable), abruptly, unexpectedly, surprisingly, plump, pop, a l'improviste, unawares, without notice, without warning, without a 'by your leave', like a thief in the night, like a thunderbolt, in an unguarded moment, suddenly, Int, heydey!, little did one think, little did one expect, nobody would ever suppose, nobody would ever think, nobody would ever expect, who would have thought? it beats the Dutch.

absence without leave, do without, early warning radar, early warning system, go without saying, strategic warning, tactical warning, warning, warning bell, warning coloration, warning device, warning light, warning of attack, warning of war, warning signal, without, without a stitch, without aim, without ambiguity, without bias, without bloodshed, without consideration, without delay, without diplomacy, without doubt, without end, without exception, without expression, without foundation, without graciousness, without moderation, without modesty, without reasoning, without rhyme or reason, without stopping, without sympathy, without thinking