I think crap is a great word. I use it frequently. It's not completely offensive. But it's expresses irritation, displeasure and frustration with only mild crudeness.
Plus, crap is a good rhyming word. You can make up lots of crap-rhyming songs. You can add pre-fixes and suffixes with complete, crapalicious abandon.
I like words that allow me to be creative.
Apparently, so does my son James. This morning in Kindergarten, the teacher told everyone to pack up their supplies. James shouted out, "Crap! I'm not done!"
The children gasped in horror. I did too (sheepishly) when the teacher told me about it. Thank goodness, she was giggling.
Sooo, me and Blurter Boy will be having yet ANOTHER conversation about bridling ye olde tongue. And that goes for me, too.