Alabama slama 

Act of having sex with a relative.

Jim-Bob had sex with his sister, hence, the Alabama slama.

Alabama slama by lonelypauly December 25, 2005

Alabama slamajama 

An orgy that involves two or more family members.

Our family reunion was good, but it got even better when a good 'ol Alabama slamajama broke out. I wish we had condoms though because now I have a nephew daughter.

Alabama slamajama by Fapulous platypus June 25, 2021