Well, that's easy. Just take what you would normally say, remove all the Christian references, and you're good to go:

God damn it --> Damn it
Jeez, what was that? --> What was that?
What the hell do you think you are doing? --> What do you think you're doing?

QUOTE:
phrases could one expect to hear, if you were in Japan and the hot bowl of soup landed in someone's lap.

Ouch! Hot! Itatata...etc (If it spilled on the Japanese guy)

I'm so sorry! Are you okay? (If Japanese guy was doing the spilling)

In the end, people are people. Just because they're Japanese doesn't mean they're going to have a drastically different response over spilling something. Hope that helps.