First thing that comes to mind is reproduction/labor/birth. Especially ducks, otters, hyenas in no particular order of brutality. Add in spiders, preying mantis, angler fish.

I’ve always heard this one used when someone is uncharacteristically grumpy or making odd little rude comments when they usually wouldn’t. Someone else would say they “must be feeling some kind of way” to explain that awkwardness.

Being detained upon arrival and immediately being sent back (if you’re lucky) is just the start.