"that's a good one" meaning in English

{
  "head_templates": [
    {
      "args": {},
      "expansion": "that's a good one",
      "name": "en-interj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "intj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "That's a very funny joke (often said to indicate that what has just been said is laughably unbelievable.)"
      ],
      "id": "en-that's_a_good_one-en-intj-SDCDEqS6",
      "raw_glosses": [
        "(informal) That's a very funny joke (often said to indicate that what has just been said is laughably unbelievable.)"
      ],
      "related": [
        {
          "word": "have a good one"
        },
        {
          "word": "job's a good 'un"
        }
      ],
      "synonyms": [
        {
          "word": "that's a laugh"
        },
        {
          "word": "don't make me laugh"
        },
        {
          "word": "yeah, right"
        },
        {
          "tags": [
            "ellipsis"
          ],
          "word": "good one"
        }
      ],
      "tags": [
        "informal"
      ]
    }
  ],
  "word": "that's a good one"
}

{
  "head_templates": [
    {
      "args": {},
      "expansion": "that's a good one",
      "name": "en-interj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "intj",
  "related": [
    {
      "word": "have a good one"
    },
    {
      "word": "job's a good 'un"
    }
  ],
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English informal terms",
        "English interjections",
        "English lemmas",
        "English multiword terms"
      ],
      "glosses": [
        "That's a very funny joke (often said to indicate that what has just been said is laughably unbelievable.)"
      ],
      "raw_glosses": [
        "(informal) That's a very funny joke (often said to indicate that what has just been said is laughably unbelievable.)"
      ],
      "synonyms": [
        {
          "word": "that's a laugh"
        },
        {
          "word": "don't make me laugh"
        },
        {
          "word": "yeah, right"
        }
      ],
      "tags": [
        "informal"
      ]
    }
  ],
  "synonyms": [
    {
      "tags": [
        "ellipsis"
      ],
      "word": "good one"
    }
  ],
  "word": "that's a good one"
}