As far as I can tell the place is totally PC in all other ways but "god damn-mother-fucker!!!
Personally I think the big difference is whether it is a generic expression of frustration (okay, comes down to personal preference and culture), or is directed at someone (always unacceptable). Since you say you are a bunch of male engineers, it is a good idea to check in once in a while and make sure that you aren't creating an environment that would appear hostile from an "outsider's" perspective, i.e. someone not a male engineer. As they say at my work, there is a difference between intent and perception, and the latter is what matters.
I say this as a female engineer working in an older/white/male/engineer-dominated industry. There are plenty of times that I have been working in that bro culture with people who have zero intent of being offensive, but can have the effect of being quite alienating all the same to anyone who doesn't fit the old boys' club stereotype.
Anyway, sorry to derail my own thread. :)