No. Absolutely not.
No. It is normal.
their own sperm
No
It's perfectly normal and safe to eat it, but if it's not your own, you can get an STD
their own sperm
Absolutely not.
Nothing happens when a man ingests his own semen.
Rodents do eat their own droppings, yes.
It is digested in the stomach. It does not contain anything harmful, if the person who it came from is disease free.
Nothing. It came from their own body and is mainly protein an water.
Giant squid eat there own kind (giant squid!)
Sperm Whales just swallow these things. They usually own sharks but sometimes sharks own them. Squids have been known to be carnivores and eat these too.