Definition of woe betide someone (or woe to someone) in US English:

woe betide someone (or woe to someone)

phrase

literary
  • Used humorously to warn someone that they will be in trouble if they do a specified thing.

    ‘woe betide anyone wearing the wrong color!’
    • ‘Yet woe betide the man who cops out and decides to skip Valentine's Day.’
    • ‘But woe betide me if something I want to watch coincides with something she wants to watch.’
    • ‘But woe to him who is alone when he falls and has not another to lift him up!’
    • ‘And woe betide you if, like me, you stumble or hesitate over your order.’
    • ‘In Canada, a motorist may turn right even if traffic lights are showing red, but woe betide him if he is involved in an accident - no arguing, he is at fault.’
    • ‘At another Hotel in Dobrich we were given little slips of paper and woe betide you if you tried to get breakfast without them, not even sight of your room key was enough.’
    • ‘But woe betide Town Council officialdom if there is another broken promise in respect of putting this bandstand into a decent and acceptable state of repair.’
    • ‘All kanji have a set number of strokes and an order in which to write them, and woe betide you if you get either wrong.’
    • ‘And woe to him inside a nonconformist clique who does not conform with nonconformity.’
    • ‘If you say you're coming for lunch at 1 then the dinner will be on the table at 1 and woe betide you if you are late.’