Related Clues:

• By surprise
• Without warning
• Unexpectedly
• Just like that
• All at once
• In a twinkling
• Quickly and unexpectedly
• All at once and unexpectedly
• Happening without warning
• Unexpectedly, abruptly
• Abruptly
• Quickly and without warning
• Without any warning
• No expectations this way
• It's not war, Ned, this way