Why not Incestuous Marriage?
As long as two People Love each other and they have reached the age of consent, what the heck.
Once the Dam breaks there is no way to stop the flood.
How about unicorn marriage - this group can marry themselves every time they stick their heads up their own A$$es.
I want to marry my dog (not for the reason you maybe thinking). I would be able to get another tax credit, use ObamaCare for the Vet bills and take out life insurance. After all dogs don't live that long.
I also want to marry my sons, no estate taxes!
See how fun changing everything can be......