A possible explanation seems to be that people also had sex at taverns. So the dog thinks its dark and decides to open a door (probably more relatable pre-electricity), but the door opens into a room where people are fucking. Some miming and facial expressions as part of the delivery could help, but wouldn't be written down.
Also a problem is that a lot of existing Sumerian texts come from after it had died out as a spoken language, so any slang or subtle meaning may have been lost
The top Ask Historians answer talks about this in more depth.
A possible explanation seems to be that people also had sex at taverns. So the dog thinks its dark and decides to open a door (probably more relatable pre-electricity), but the door opens into a room where people are fucking. Some miming and facial expressions as part of the delivery could help, but wouldn't be written down.
Also a problem is that a lot of existing Sumerian texts come from after it had died out as a spoken language, so any slang or subtle meaning may have been lost
It could just straight up be a pun and we would have no idea.
That was my first thought too, like maybe tavern was also slang for seeing something.