autoinsemination
When a character cums into his/her own vagina/anus using his/her own penis.
The cum must be somehow transported directly into the orifice using methods including but not limited to:
- directly bending the penis back (ex: Danbooru post #481023)
- using a tube (ex: Danbooru post #291428)
- using a portal (ex: Danbooru post #3627283)