It's the two
words brave and
stupidity bundle together.
It is to make a brave choice, when a lot of
people would consider it stupid. Usually when the situation is classified as a "Suicide Mission", many would decline but only the ones with the most bravitity will accept.
General: Our men are pinned down and running out of ammo, we need someone to get there and help them EVAC immediately!
Non-Bravitity Soldier: No way I am going, that's
suicide!
Bravitity Soldier: I will
go General!
General: Alright, Bravitity Soldier, go take them ammo and help them EVAC. I'll get a helo for an immediate EVAC.
Non-Bravitity Soldier: That man is so stupid, he is going to get himself killed!
General: No Non-Bravitity Soldier, he is brave, and stupid. He is the
definition of Bravitity.