INCESTion is the act of fucking your wife while she's pregnant and sticking your penus soooo far in that it goes In your babies mouth. Therefore, you are somewhat being an incest.
That incestion last night was sooo good. My baby is gona come out sucking dick like a pro.
Getting your own mother pregnant, then getting that daughter/sister pregnant. Therefore, it's a sister within a sister. Inception + Incest = Incestion
Woah, you got your mom pregnant? Then that child? INCESTION!
When one member of your family wants you to have sex with another member of your family.
"I want my sister to fuck my dad!"
When doing 69 with an exact replica of oneself, the person is giving pleasure to themself while reciving pleasure from themself, thus creating a split in the universe
-I saw a guy 69ing with his clone
-Are you crazy? I heard incestion was impossible!