The act of a father and son interlocking into an intense make-out session. Weather the relationship is gay or not, both members deeply enjoy the moment.
I walked into my homies room right when him and his dad were doing The Mongan!
Example:
Dude: Babe, now do the montana slurpy
Girl: Fine Babe. *insert noises of a mixture between slurping dick and Hannah Montana's "Best of Both Worlds".
The Montana Zombie Apocalypse is a risky yet rewarding sexual act involving an individual that’s infected with an STD and the other a person with autism. The person with autism eats the other persons ass until the STD is transmitted to the autistic person. Once diagnosed, both individuals must convince the doctor that diagnosed them for a threesome and therefore repeat the cycle.