Green’s Dictionary of Slang

fat n.

1. [mid-19C; 1960s] (Aus./US) money.

2. [late 19C–1950s] (Aus./N.Z., also fatman) a generic term for the business elite, the wealthiest members of the community.

3. [1930s+] (Aus./N.Z.) an erection; esp. in phr. crack a fat

4. [1930s+] (usu. gay) a fat person; esp. used in small ads, usu. in comb with ‘fems’ (i.e. effeminate rather than macho men), e.g. no fats or fems.

5. (US) the vagina.

In phrases

crack a fat (v.) (also crack a fatty)

1. [1940s+] (Aus.) to achieve an erection .

2. in fig. use, to become excited (in non-sexual contexts).

hit the fat (v.)

[1940s] (US) to win a large sum of money.

SE in slang uses

In phrases

fat is in the fire, (all) the

see separate entry.

fat scraps and glorious bits (n.)

[17C] (UK Und.) a sound beating.

In exclamations

fat’s a-running!

[late 19C–1930s] (UK Und.) a phr. used to indicate that a loaded van is passing along the street and may be robbed, to the greatest possible extent, by opportunists.