We use the word 'man' in such context quite commonly.
[Added note: To avoid ambiguity] In all these cases, I'm talking to a man. He's right there, in front of me.
"Man, it's not that easy!"
"Look man, don't mess with me."
"Ah, bang on, man!"
What if I'm talking to a woman? Can I still use 'man' as 'guys' (which is now considered as an epicene term)? I can call girls 'guys' informally.