A stock phrase in Japanese pop culture supposedly used by the wife in a newly-wed couple to invite her new husband to bed.

Kyūjitai form of 私生児 (“illegitimate child”)

one day, 24 hours / the daytime, the period from dawn until dusk / (figuratively) a short period of time / one day, someday, an unspecified day / the first day of the month

a birthday

regular day off (e.g. closed every Monday)

the twentieth day of the month / twenty days / Short for 二十日鼠 (hatsuka nezumi): a house mouse

幾日も幾日も: day after day

a lucky day, auspicious day

(rare) one's birthday

Saturday