Green’s Dictionary of Slang

1. to stuff with food.

1937–84

Partridge DSUE (1984) 957/2: from ca. 1885.

2. (UK black) to fill up, to cram.

1999

(con. 1979–80) A. Wheatle Brixton Rock (2004) 198: His pickney will ram-jam all the nurseries in SW9.