A ridiculously large cat weighing at least 40 lbs. When written as a "40Lb cat," is misread as "hobb cat" as a way for the reader's brain to make sense of the description since there is no way "40-lb cat" could be right!

May also be used to describe a Hobbit-eating cat.

The horrible moment when you realise that you have accidentally done something very slightly wrong which has very bad (usually embarassing) implications for you. This is typically the moment of realisation that you just sent a dirty text message to a close member of family, typically your mother, rather than the intended recipient.