Green’s Dictionary of Slang

1. (bingo) the number 13.

1980		T. McClenaghan Submariners I ii: On its own, number two, unlucky for some, thirteen.
2001		J. Burkardt ‘The Bingo Code’ Wordplay 🌐 13: unlucky for some.

2. £13.00.

1989

(con. 1950s–60s) in G. Tremlett Little Legs 198: unlucky for some £13.