In
Quake 2, to jump in the air, with
quad damage, and fire
the BFG at the ground, in the hopes of gaining some
serious altitude .
Of course, the only way to survive this is with 200 red armor, a power shield (which loses its cells as the BFG fires but still helps a little) and the Auto-Doc tech. Of course, having invulnerability really helps.
See also: rocket jump