A couple enemies have special rules for interactions, outside of the standard ones for mediums. This applied to the Cockhugger and the Centipede. The Cockhugger has a chance to spawn as pink-ish variant from an egg. from there, all you need to do is get hit. For the centipede, we have placed in the world a couple of them with a more orange-y color palette. Power punching their rear will trigger an animation ^^
Just today I found out about the Cockhugger variant on my own (awesome mechanic btw, it's like shiny-hunting but sex happens). Gotta collect some samples y'know?
I thought all interactions were punch-based). Can't wait to find that cute Centipede~
Oh! Also some mini-boss feedback; the rolliboy and the mud momma (buggier) are super easy to cheese by walking through them.