Number Ciphers

ive seen some number ciphers around but have no clue what they mean or how to solve it. They look kinda like this (got this from a thread)
34 34 20 34 66 20 3230 20 34 65 20 34 6620 35 34 20 32 30 2034 33 20 35 32 20 3466 20 35 33 20 35 3320 32 30 20 34 64 20 34 35

 

Selvut has one I think is BUN BUN BUN BUN BUN BUN BUN BUN

 

I think he's asking which cipher it is

 

I'm asking how to cipher

 

Alright well I'm not sure of the context for this puzzle so I hope I'm not unintentionally giving something away :(
After getting into this cryptic shit, you kind of learn to distinguish a hex string...
34 34 20 34 66 20 32 30 20 34 65 20 34 66 20 35 34 20 32 30 20 34 33 20 35 32 20 34 66 20 35 33 20 35 33 20 32 30 20 34 64 20 34 35
Decoded from hex:
44 4f 20 4e 4f 54 20 43 52 4f 53 53 20 4d 45
Decoded again from hex:
DO NOT CROSS ME

tl;dr double encoded hex

 

Still have no clue how to cipher

 

That is some creepy stuff