鐵膠 [铁胶]

Jyutping tit3 gaau1
Pinyin tiě jiāo

Definitions (粵典–words.hk)
  1. 名詞
    對鐵路​迷​嘅​貶​稱​（​膠經​常用​喺​貶​稱​）​（​量​詞​：​個​）
    a derogative term for railway enthusiasts; literally: railway plastic (also see 膠gaau1)