A mouth washed out with soap

this morning I was looking in my wallet for a twenty dollar bill I had put in there. it was gone and I exclaimed, "What the heck?" Grace heard me and instantly kept repeating "what the heck! what the heck!" and then started making a song out of the phrase. So not only do I feel bad for saying "what the heck" (it is not the most ladylike term) but now my child is singing it with glee as a constant reminder of my verbal faux pas.