In that context it's a Colombian regionalism used to express an exaggeration commonly used with vulgarity.
For example, someone wants to highlight the cold weather yesterday:
"ayer hacía un frío ni el vulgar word here"
or multiplying the vulgarity factor
"ayer hacía un frío ni el triple vulgar word here"
I can think of a similarity with expressions like "it's cold as a mtfk."
Only use it with close friends.
edit:
More examples (common in Colombia - all vulgar):
There was a huge line:
Había una fila ni la hijueputa
(In Colombia we say hijueputa instead of "hijo de puta")
He had a really big knife
El tenía un cuchillo ni el hijueputa
Complaining about yesterday's weather
Ayer hacía un calor ni el hijueputa