"off like a prom dress" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "off"
      },
      "expansion": "off",
      "name": "m"
    },
    {
      "args": {
        "1": "en",
        "2": "off like a bride's nightie"
      },
      "expansion": "off like a bride's nightie",
      "name": "m"
    }
  ],
  "etymology_text": "Pun on two senses of off, with the implication that a couple at a prom are likely to have sexual intercourse. Compare off like a bride's nightie.",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "off like a prom dress (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Canadian English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English similes",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "When we heard the police car pull up, we were off like a prom dress.",
          "type": "example"
        }
      ],
      "glosses": [
        "Making a start, or departing, very rapidly."
      ],
      "id": "en-off_like_a_prom_dress-en-adj-G7BhQHQ-",
      "links": [
        [
          "Canada",
          "Canada"
        ],
        [
          "US",
          "American English"
        ]
      ],
      "qualifier": "simile",
      "raw_glosses": [
        "(simile, slang, Canada, US) Making a start, or departing, very rapidly."
      ],
      "tags": [
        "Canada",
        "US",
        "not-comparable",
        "slang"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-off like a prom dress.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/1/1a/En-au-off_like_a_prom_dress.ogg/En-au-off_like_a_prom_dress.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/1/1a/En-au-off_like_a_prom_dress.ogg",
      "tags": [
        "Australia"
      ],
      "text": "Audio (AU)"
    }
  ],
  "word": "off like a prom dress"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "off"
      },
      "expansion": "off",
      "name": "m"
    },
    {
      "args": {
        "1": "en",
        "2": "off like a bride's nightie"
      },
      "expansion": "off like a bride's nightie",
      "name": "m"
    }
  ],
  "etymology_text": "Pun on two senses of off, with the implication that a couple at a prom are likely to have sexual intercourse. Compare off like a bride's nightie.",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "off like a prom dress (not comparable)",
      "name": "en-adj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "categories": [
        "American English",
        "Canadian English",
        "English adjectives",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English similes",
        "English slang",
        "English terms with audio links",
        "English terms with usage examples",
        "English uncomparable adjectives"
      ],
      "examples": [
        {
          "text": "When we heard the police car pull up, we were off like a prom dress.",
          "type": "example"
        }
      ],
      "glosses": [
        "Making a start, or departing, very rapidly."
      ],
      "links": [
        [
          "Canada",
          "Canada"
        ],
        [
          "US",
          "American English"
        ]
      ],
      "qualifier": "simile",
      "raw_glosses": [
        "(simile, slang, Canada, US) Making a start, or departing, very rapidly."
      ],
      "tags": [
        "Canada",
        "US",
        "not-comparable",
        "slang"
      ]
    }
  ],
  "sounds": [
    {
      "audio": "En-au-off like a prom dress.ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/1/1a/En-au-off_like_a_prom_dress.ogg/En-au-off_like_a_prom_dress.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/1/1a/En-au-off_like_a_prom_dress.ogg",
      "tags": [
        "Australia"
      ],
      "text": "Audio (AU)"
    }
  ],
  "word": "off like a prom dress"
}