A Hanoi high five is derivative from the term used in the film 'Tropic Thunder', but has evolved into a sexual move.
A Hanoi high five is where your partner is on the bottom preferably , when they're are at the point of orgasm (liberating the south) you land a bomb/grenade to the dome. There are variations of the
finishing move, i.e throwing them out of your house/flat/village/country ,
ejaculating or ask them to concede victory.
This move can also be used
on the back foot, an example below.
The first example would be in a forced sexual situation where
you are not the aggressor.
1. He mounted me and when he was about to liberate the south, Bam Hanoi High five.
Another example for
emergency situations
1. You are
making love, she decides to tell you at the point of liberation "hey you want to meet my parents", Hanoi high five, a perfect gesture to decline that meet.