"Frak" is part of our culture? Um, no. Not even close.
No one said that "frak" was "part of our culture". However, most of the TV viewing audience in the English speaking word has heard it, or heard of it, or has an inkling of what it means.
Can you think of other 'alien' words like those two that you can hear as part of our 'collective culture'?
The vast majority of the English speaking TV world has never watched a split second of BSG. Ask someone what "frak" means out of context and very few people would have the slightest idea. Don't mistake your sci-fi fandom for some widespread phenomenon that isn't there.