Green’s Dictionary of Slang

pig v.1

1. [late 17C+] to live (with); often in phrs. below.

2. [late 17C+] to live in a slovenly manner; thus pig it

3. [20C+] to eat, esp. in a greedy fashion, to overeat.

4. [1950s] to provide with food.

In phrases

pig down (v.)

[1980s] to eat hurriedly and greedily.

pig in (v.)

1. [late 17C+] to share a home, to live (with); usu. as pig in with.

2. [20C+] to gorge oneself; often as exhortation pig in!

pig it (v.) (also pig out)

1. [19C+] to live in squalor, albeit unworried by that squalor.

2. [1900s–30s] to renege.

3. [2000s] to prosper.

pig out (v.) (also pig it)

1. [mid-19C; 1930s] to die.

2. [mid-19C+] (also pig up) to overeat massively; ext. as pig out on (a food or drink).

3. [1970s+] (also pig up) to overindulge in anything.

4. [1990s+] to treat someone to a (large) meal.

pig together (v.) [the proximity resembles pigs in a sty]

[late 17C–mid-19C] to live together, often spec. to sleep together.