The phrase "
God Damnit", which when expressed in a grammatically correct fashion would read "God Damn It," is a vulgarity used to express frustration. It's literal definition is "
May the Christian God Damn it to Hell". In slang, it is a phrase used in a generally
non-religious context. For example, if one cannot
get an electronic device to
work properly, one might exclaim "
God Damnit!", meaning that you are so upset with the device you wish that
God would condemn it to eternal damnation.
It is rarely used literally, and is considered a lesser of vulgarities, though to the extremely religious it is considered highly offensive. In the Christian faith it is considered a violation of one of the ten commandments.