Green’s Dictionary of Slang

short strokes n.

also hard strokes, short digs, short shoves

[late 19C+] the final stage of sexual intercourse, immediately preceding male orgasm.

In phrases

on one’s/the short strokes (also down to the short strokes, getting to the short strokes)

1. of a man, approaching orgasm.

2. in fig. use, running out of time, approaching the end, nearing a conclusion.