Definition of go off the deep end in US English:

go off the deep end

phrase

informal
  • 1Give way immediately to an emotional outburst, especially of anger.

    • ‘I might have suggested your name at some point but that's not reason to go off the deep end at me!’
    • ‘Some Bulgarian leaders, and its media, went off the deep end after a Bulgarian gymnastics hopeful was judged worthy of silver, but not gold.’
    • ‘He was right, she had no business going off the deep end like that in front of anyone.’
    • ‘If anyone out there thinks the Globe & Mail is biased, the Calgary Herald, Calgary Sun and National Post have absolutely gone off the deep end since the election.’
    • ‘With each word Julius increased volume, he started to go off the deep end reading me his version of the riot act.’
    • ‘When my soon-to-be ex discovered this budding romance, he went off the deep end - ranting, raving, smashing framed wedding invitations, and shredding my underwear.’
    • ‘I just went off the deep end and I said, ‘Hey, this is going too far’.’’
    • ‘Something about Marin was soothing, keeping him calm at times he would've normally gone off the deep end.’
    • ‘A few may go off the deep end screaming about human rights, but there are others which are both clear-eyed and clear-headed while being concerned about human rights.’
    • ‘I thought they'd go off the deep end but they weren't surprised at all.’
    1. 1.1US Go mad; behave extremely strangely.
      ‘they looked at me as if I had gone off the deep end’
      • ‘Even for a company known for reinventing itself with each new production, it seemed that Headlong Dance Theater had finally gone off the deep end when its new production was announced.’
      • ‘The one thing that hadn't passed was her determination to be separated legally from her mother, who we both knew had gone off the deep end permanently and had even been trying to sell all of Victoria's belongings.’
      • ‘As far as warning signs go, two people I knew went off the deep end during various mind expansion attempts.’
      • ‘And pretty soon the fridge was empty and we're sitting there in the kitchen, laughing so hard about heart disease and strokes that I thought we'd both gone off the deep end.’
      • ‘They glanced at each other like she had gone off the deep end, but Ashley obeyed and retrieved her cordless phone from the kitchen.’
      • ‘How should the rest of us regard a once-formidable mind after it has gone off the deep end?’
      • ‘I don't know if she's just goofing around or if she's totally gone off the deep end.’
      • ‘It was like a two-year period when I went off the deep end and it culminated in that ludicrous mess.’
      • ‘My mother has always been crazy but she finally went off the deep end and severed ties with me and her mother who I stay with.’
      • ‘Toddlers are also creatures of habit, which in the end is perhaps the only thing that saves a parent from going off the deep end.’