Man alive!

[Alicelily]

Phoebe: It's fine. I mean, this is something that you've been thinking about since you were what,14?"(She's referring to the Halloween picture.)

Rachel: No, I was ten. I just developed early.

Phoebe: (looking at the picture again) Man alive!

=>What does "Man alive!" mean?

[Tdol]

It's an expression of surprise or shock, like 'Good God', etc.