what if aliens are grossed out by human body mods, like, even basic things, like ear piercings and tattoos. like, you stab yourself with needles, put metal in the wounds deliberately preventing normal healing? thats hella gross. and then of course less common body mods are even stranger to them. its even stranger when you remember that tattoos and piercings arose in a lot of different cultures it makes sense, in a way. humans, for all the talk of their survival instinct and force of will, are pretty bad at self-preservation on a day to day basis
on the contrary, what if they have their own body mod culture? beyond what human tech is capable of, and not anything we’d ever come up with. like, transdermal implants exist for us, but what if some aliens have those instead of tattoos because their “vision” doesn’t include visible light. or maybe their skin changes color naturally, and permanent color changes would hinder whatever color change is meant for in their lives. maybe their body mods are something their senses can detect, but ours can’t.
strong enough echolocation can sort of detect internal structures, so body mods invisible to us could theoretically sound really cool. if their biotech is up for it, aliens primarily sensing through smell could have scent gland implants.
or maybe they’re shapeshifting, or something similar, and its a societal norm that you have body mods, and they’re surprised that humans do so little. like, form changes are so normal, that no one looks like they would’ve normally, everyone is the ideal version of themselves, and now that sort of segues into plastic surgery and what aliens would make of that.