Is this a curse word?

"SNAP"??!! Is this a substitute for a curse word? I have heard one of my children say this over and over lately. NPayne says it's a substitute for a curse word. I thought is was an innocent way to express a little frustration, like saying, "OH FIDDLE STICKS" or something along those lines. Anyone know? Anyone? Anyone? Bueller? Bueller? By the way, is it curse word or cuss word?