"big fat zero" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "big fat zero",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "coordinate_terms": [
        {
          "word": "Big One"
        },
        {
          "word": "big one"
        },
        {
          "word": "big two"
        },
        {
          "word": "Big Three"
        },
        {
          "word": "Big Four"
        },
        {
          "word": "big five"
        },
        {
          "word": "big six"
        },
        {
          "word": "big eight"
        }
      ],
      "glosses": [
        "Nothing at all."
      ],
      "id": "en-big_fat_zero-en-noun-jLIFFrx4",
      "links": [
        [
          "Nothing",
          "nothing"
        ],
        [
          "at all",
          "at all"
        ]
      ],
      "raw_glosses": [
        "(slang) Nothing at all."
      ],
      "tags": [
        "slang"
      ]
    }
  ],
  "word": "big fat zero"
}

{
  "coordinate_terms": [
    {
      "word": "Big One"
    },
    {
      "word": "big one"
    },
    {
      "word": "big two"
    },
    {
      "word": "Big Three"
    },
    {
      "word": "Big Four"
    },
    {
      "word": "big five"
    },
    {
      "word": "big six"
    },
    {
      "word": "big eight"
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "big fat zero",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English nouns with unknown or uncertain plurals",
        "English slang"
      ],
      "glosses": [
        "Nothing at all."
      ],
      "links": [
        [
          "Nothing",
          "nothing"
        ],
        [
          "at all",
          "at all"
        ]
      ],
      "raw_glosses": [
        "(slang) Nothing at all."
      ],
      "tags": [
        "slang"
      ]
    }
  ],
  "word": "big fat zero"
}