What does Boxing Day have to do with boxing?
early 15c., from juice (n.) + -y (2). Figurative sense "weathly, full of some desired quality" is from 1620s; sense of "lively, suggestive, sensational" is from 1883. Related: Juiciness.
Interesting in a sexy or scandalous way; sensational; racy: He spared us none of the juicy details (1883+)