What words do you or people you know substitute for obscenities and blasphemies?

Frigging, frikking, freaking, frakking. Frakk.
Stuck like a duck in the muck.

Saatana peijakas perkele. Which makes Finnish people laugh, as saatana and perkele are still in use today, but peijakas is a very old-fashioned and very mild word. Saatana is a loan word, meaning satan, and peijakas and perkele are names for spirits that Christianity turned into devil names. I just looked it up, and Perkele comes from the name of the Baltic thunder god (the Finnish one was Ukko, remembered in ukkonen, the word for thunder). So the next time I say perkele! I will imagine Chris Hemsworth as Thor turning up to save the day.