Oh! That would be in qb-core > shared > items.lua

Take a look at the rolling paper item:

['rolling_paper'] = {
  ['name'] = 'rolling_paper',
  ['label'] = 'Rolling Paper',
  ['weight'] = 0,
  ['type'] = 'item',
  ['image'] = 'rolling_paper.png',
  ['unique'] = false,
  ['useable'] = false,
  ['shouldClose'] = true,
  ['combinable'] = {
    accept = {
      'weed_white-widow',
      'weed_skunk',
      'weed_purple-haze',
      'weed_og-kush',
      'weed_amnesia',
      'weed_ak47'
    },
    reward = 'joint',
    anim = {
      ['dict'] = 'anim@amb@business@weed@weed_inspecting_high_dry@',
      ['lib'] = 'weed_inspecting_high_base_inspector',
      ['text'] = 'Rolling joint',
      ['timeOut'] = 5000,
    }
  },
  ['description'] = 'Paper made specifically for encasing and smoking tobacco or cannabis.'
},