Attractive female. Stems from a commonly misheard lyric in AC/DC's song "You Shook Me All Night Long", which is "She was a fax machine". The actual lyric is "She was a fast machine".
A kid in class who hears others silently say an answer to a question, and they say it louder so that the teacher hears and it makes them look super smart when they're stealing people's thunder.
Person: "I just bought a fax machine. I think I will use it to send disturbing faxes to my friends." (note: The faxes will end up back in his fax machine.)