A person how masted the art of bailing.
A masterbailer bails out of anything from internet convos to real needs while occasionally dropping some completely lame excuses.
Jude: Your bailed out of the chat last night, your such a masterbailer!
Nancy: Sorry man, I swear I fell asleep on the keyboard.
Jack: Why didnt Adam show up last night?
John: He said he had to to go somewhere.
Jack: He's such a masterbailer!