So imagine an alien race with only one gender or who have like really different gender characteristics or something.
First, they have trouble understanding that there are genders, because we look really similar regardless of gender, two arms, two legs, no colour scheme to separate “male” from “female” exclusively.
Second, no matter how many times some humans say there are only two genders, others say there are many. It seems, the aliens conclude, that all humans have their own way of defining how many genders there are, and how these are allowed to interact.
Third, the aliens soon discover that the humans get really awkward if you bring up mating (“fucking”) with another human around. And as we all know, humans are space orcs and nothing seem to faze them, so having found this small weakness, the aliens likes to exploit it and mess with the humans as often as they can.
“Are you and officer Alvarez a couple?”
The humans looked at each other. Their faces scrunched together and assumed a colour resembling the mess hall walls. The ensign could barely contain its delight.
“We are both men, ensign. Just because we are the only two humans…”
The human trailed off, blushing harder by the minute and refusing to meet the eyes of its fellow. The other human looked surprised and then a small smile erupted on its face. It reached out its hand and placed it carefully on top of the others knee.
“We are not a couple, but I understand your confusion,” it proclaimed. “I mean, we are usually keeping pretty close.”
The ensign nodded both antennae slowly, not sure where this was going.
The human who had spoke last moved closer to the other. The ensign immediately got a bad feeling. The human put its darker hand on the paler ones jaw and smiled sweetly before leaning in.
The ensign felt all vital fluids drain his extremities. Meeting mouths was highly inappropriate, not to mention unsanitary! Gagging, the alien fled.
The ensign leaned against the wall, weak legged, as its sensitive antennae picked up the scattered conversation between the humans.
“To mess… mess with them.”
“Also… anted to kiss you… really long time.”
More noices and the ensign moved away. There was certainly a downside to teasing the humans.