Green’s Dictionary of Slang

1. (US campus) a socially unappealing, studious student.

1988

Eble Campus Sl. Oct. 5: hobbit – particularly abnormal, overly studious individual who displays an egregious defiance of personal hygiene.

2. (UK prison) a compliant prisoner.

2003		Observer Crime 27 Apr. 28: Hobbit. A prisoner who complies with the system. Also, hobbit hole: place where the Hobbits go, such as the TV room.
2004		N. ‘Razor’ Smith A Few Kind Words and a Loaded Gun 138: He was a proper hobbit and sucked up to the screws.

3. (UK Und.) an incompetent, a fool.