1. (Aus.) a $20 note.
|More You Bet 66: The ‘$20 note’ is known a ‘red-back’, after the spider, or as a ‘lobster’, or a ‘lobby’ for short, due to colour of a $20 note resembling that of a boiled lobster.|
|Tales of the Honey Badger [ebook] [They were] $1 a pair [...] So I laid out two lobsaters and got meself 40 pairs.|
2. (Aus. prison) a 20-year jail sentence.
|Aus. Prison Sl. Gloss. [Internet] Lobster. Twenty year sentence. Becoming obsolete.|