The mutually beneficial arrangement allows the attractive girl to have menial tasks performed for her, and make herself look more beautiful by comparison. The unattractive companion(s) get to pick up the higher quality male scraps the attractive girl draws in.
Named after a long, graceful ocean liner surrounded by several ugly, short, tugboats as she enters harbor.
RW: "No man, I farted outside and Tugboated into your office."
KT: "I commend you on your respect for my office."
Bill: "Thats weird, dude. I'm out."