I say 'fething warp', combining various made-up sci-fi profanities from different Warhammer 40k authors.
'Feth' is a tree god from a forest planet, though usage of his name is equivalent to 'fuck'. It was also one of the buildings on my campus, which confused a lot of people.
The 'Warp' is a parallel dimension of emotion and storms and is literally hell.
Saying 'fething warp' is essentially a tamer way of saying 'fucking hell', which I say anyways when I'm upset.