A medic typically performs Rambo revives when he is a n00b just to get lots of points or does it for the lulz when he is a troll who likes to fck his teammates.
The "Rambo" part comes from the typical Rambo-style dash into groups of enemies just to get points for reviving teammates lying there. However, unlike Rambo, it is very that they both die in a matter of seconds.
Medic: *revives soldier* I got ya all fixed up!
Soldier: *dies again by same enemies*
Soldier: You just pulled another Rambo revive on me, FFS STOP REVIVING ME F*CKING MORON, MY KDR IS DROPPING BELOW 1 THIS WAY!!ONE!