One who believes that certain values typically associated with the far left, such as environmental sustainability and animal rights, are fully compatible with (or even a natural extension of) their libertarian values. Essentially, one who believes in compassion but doesn't believe that robbing Peter to pay Paul (i.e. government appropriation of our income) is the least bit compassionate.
A: You're a vegan? I thought you were just one of those nutjobs that believed we should eliminate the Federal Reserve and legalize heroin.
B: You know me, bleeding-heart libertarian.