Green’s Dictionary of Slang

hole (out in one) v.

[golfing imagery]

(Aus.) to become pregnant after one’s first act of sexual intercourse, esp. on one’s marriage night.

[Aus]N. Pulliam I Travelled a Lonely Land (1957) 234/1: hole out in one – a gal who makes a bad mistake, gets in trouble the first time she steps out.
[US]Maledicta IV:2 (Winter) 199: Holed out in one is pregnant after only one sexual act.