Wherein ZZS and WKX sleep together...
Thank you Emma P for proofreading!
Note
1. 丙辰年，腊月初八. Date expressed using the traditional lunisolar calendar (lunar months) and sexagenary cycle aka Stems-and-Branches.
The La month is the 12th month in the lunisolar calendar.
The Bingchen year is the 53rd year in the sexagenary cycle.
Since, according to the lunar calendar, the new year begins either on the new moon before the spring equinox, or the one after the winter solstice, making each year begin on spring — when WKX says he wants to stay till next spring, it means he wants to stay until New Year's eve. And since they are on the 8th of the La month/12th month, the duration of their stay is either approx 20 days or, if the year has a leap month/13th month after the 12th month, 50 days.
As per the next chapter, the year doesn't seem to have a leap month after the 12th month. So, at this point, WKX plan on staying for about 20 days.
Since there are only 60 years in the sexagenary cycle, another element — generally the regnal year/era — is necessary to date events. Here it would be the fictional Daqing or Rongjia.
2. WKX describe their rapport as "你侬我侬" or lit. "you and me, me and you/you are me, I am you". From poem 我侬词 by 管道升 that describes intimacy between lovers.
3. 禄山之爪 or "Lushan claw" in the original. Refers to general An Lushan who scratched Yang Guifei's breast by accident. Which was a big deal because they feared Emperor Xuan Zong (Yang Guifei's husband) would see the mark. Means a brusque move in flirtatious rapport.
4. 死猪不怕开水 collq. translated literally. Self-explanatory I think.