OK, along the lines of Zut Alors! TV shows love this French expression, of “Holy Blue!” (Like Holy Cow makes any more sense?) So, where does “holy blue” and “holy cow” come from? A holy blue cow?
“They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV
“Sacrebleu” comes from the fact that “bleu” sounds a little like “dieu”, and “dieu” is god (of course, “sacré” means holy or sacred.) Therefore by using “sacrebleu” you can swear without being hit by a bolt of lightning.
Oh! I got it now! 
…Thanks! 
“They’re coming to take me away ha-ha, ho-ho, hee-hee, to the funny farm where life is beautiful all the time… :)” - Napoleon IV