Is the phrase "that guy so inch" related to Putonghua?
It is Cantonese

串 /cyun3 /
[7] [粵] [adj] arrogant; cocky | [Var] 寸

&quot;that guy so inch&quot; is literal translations of &quot;嗰條友咁寸(串)&quot; in Cantonese.
The 'arrogant; cocky' definition of 串 is not used in Mandarin.
&quot;嗰條友咁串&quot; in Mandarin would be &quot;那傢伙太囂張了&quot; meaning &quot;that guy is so arrogant&quot;

咁串
太嚣张了。