Vogelfrey is an medieval way of spelling Vogelfrei (which some taffer already has as name ).

Being vogelfrei first means being an outlaw, like Robin Hood or, say, Garrett. You aren't protected by any laws and people are free to do to you whatever comes to their mind - as long as they get you.
Secondly, however, vogelfrei can be read as 'free like a bird'. Which fits the above a lot (especially that thing with Garrett).

Oh yes, I am a Thief Player. You're welcome.