An inept move. In Quake, one can jump extra high by firing a rocket at her feet while jumping. Sometimes, a user forgets she is carrying a railgun instead of a rocket launcher. When she attempts to jump to a really high place, she succeeds only in a small but stylish hop as she fires her railgun at her feet. Example: Nuts, I'd've had the BFG if only I hadn't railjumped into the lava.
RAILJUMP
Meaning of RAILJUMP in English
Slang English vocab. Английский сленговый словарь. 2012