And there we go... again!

lib/Endpoints.js

@@ -1,24 +1,29 @@
-module.exports = [
-  'sfw',
-  'nsfw',
-  'neko',
-  'lewdneko',
-  'shinobu',
-  'trap',
-  'bully',
-  'cry',
-  'hug',
-  'kiss',
-  'lick',
-  'pat',
-  'smug',
-  'highfive',
-  'nom',
-  'bite',
-  'slap',
-  'wink',
-  'poke',
-  'dance',
-  'cringe',
-  'blush'
-]
+module.exports = {
+  sfw: [
+    'waifu',
+    'neko',
+    'shinobu',
+    'bully',
+    'cry',
+    'hug',
+    'kiss',
+    'lick',
+    'pat',
+    'smug',
+    'highfive',
+    'nom',
+    'bite',
+    'slap',
+    'wink',
+    'poke',
+    'dance',
+    'cringe',
+    'blush'
+  ],
+  nsfw: [
+    'waifu',
+    'neko',
+    'trap',
+    'blowjob'
+  ]
+}

lib/WaifuPics.js

@@ -1,39 +1,31 @@
 const fetch = require('node-fetch')
-const ENDPOINTS = require('./Endpoints.js')
+const endpoints = require('./Endpoints.js')
 
 const API_URL = 'https://waifu.pics/api'
 
-async function parseResponse (response) {
-  if (!response.ok) {
-    const failure = await response.text()
-
-    throw new Error(failure)
-  }
-
-  return response.json()
+/**
+ * @param {string} endpoint An endpoint contained in {@link https://waifu.pics/api/endpoints}
+ * @returns {Promise}
+ */
+function _request (endpoint) {
+  return fetch(`${API_URL}${!endpoint.startsWith('/') ? `/${endpoint}` : endpoint}`).then((response) => response.json())
 }
 
 const WaifuPics = {
   /**
-   * @param {string} endpoint An endpoint contained in {@link https://waifu.pics/api/endpoints}
-   * @returns {Promise}
-   */
-  fetch (endpoint) {
-    return fetch(`${API_URL}${!endpoint.startsWith('/') ? `/${endpoint}` : endpoint}`).then(parseResponse)
-  },
-
-  /**
-   * @returns {Promise<string[]>}
+   * @returns {Promise<Object>}
    */
   endpoints () {
-    return this.fetch('/endpoints')
+    return _request('/endpoints')
   }
 }
 
-for (let endpoint of ENDPOINTS) {
-  WaifuPics[endpoint] = function () {
-    return this.fetch(endpoint)
-  }
-}
+Object.keys(endpoints).forEach((type) => {
+  WaifuPics[type] = {}
+
+  endpoints[type].forEach((category) => {
+    WaifuPics[type][category] = () => _request(`/${type}/${category}`)
+  })
+})
 
 module.exports = WaifuPics