老鐵 [－铁]

Jyutping lou5 tit3
Pinyin lǎo tiě

Definitions (Wiktionary)

noun, as term of address, often, slang
(my) brother; mate; man; buddy
- 扎心了，老鐵。
  扎心了，老铁。
  zhā xīn le ， lǎo tiě ．
  Your words touched my sore spot, man. (slang)

老鐵 [－铁]

Jyutping
Pinyin lǎo tiě

Definitions (CC-CEDICT)

(slang) very close friend
bro

Examples (Wiktionary)

Mandarin
扎心了，老铁。
扎心了，老鐵。
zhā xīn le ， lǎo tiě ．
- Your words touched my sore spot, man. (slang)
- Life is hard, man. (slang, alternatively)