Abhi it's also a reference used in sado masochism. The term GIMP refers to someone whose sexual fetish is to dress in a rubber mask or bodysuit and then be restrained and dominated.
This is what really makes the word frowned upon in society, and it was always a bad idea to name a software package in this way - it's distasteful, yet the developers went with it, using the word as an acronym. Perhaps innocently, but that's hard to believe.