"not know what hit one" meaning in All languages combined

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "verb"
      },
      "expansion": "not know what hit one",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English negative polarity items",
          "parents": [
            "Negative polarity items",
            "Terms by semantic function"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "She didn't know what hit her when her boyfriend broke up with her.",
          "type": "example"
        },
        {
          "text": "My friend didn't know what had hit him when I poured a bucket of water over his head.",
          "type": "example"
        }
      ],
      "glosses": [
        "To be extremely surprised by an event."
      ],
      "id": "en-not_know_what_hit_one-en-verb-3wpznIPZ",
      "links": [
        [
          "surprised",
          "surprised"
        ]
      ]
    }
  ],
  "word": "not know what hit one"
}

{
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "verb"
      },
      "expansion": "not know what hit one",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English negative polarity items",
        "English terms with usage examples",
        "English verbs",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "examples": [
        {
          "text": "She didn't know what hit her when her boyfriend broke up with her.",
          "type": "example"
        },
        {
          "text": "My friend didn't know what had hit him when I poured a bucket of water over his head.",
          "type": "example"
        }
      ],
      "glosses": [
        "To be extremely surprised by an event."
      ],
      "links": [
        [
          "surprised",
          "surprised"
        ]
      ]
    }
  ],
  "word": "not know what hit one"
}