Andie is more honest than we are when it comes to obnoxiously loud toys:
My son has a few toys that are simply louder than loud. Our solution until recently has been to either a) let the batteries run out and tell him that the toy is broken (I know, shame on us) or b) remove the batteries before he realizes that the toy even makes sounds.
Although our tactics have kinda worked, they are just too deceptive, and I already have a guilt complex. I was speaking to a neighbor about loud kid toys, and she had a fantastic idea: put packing tape over the toy's speaker. It will muffle the siren song of most toys enough so that they won't drive mom & dad crazy, but will still allow Junior to enjoy the sound of the toy.
When my son was a toddler, he would have made it his personal mission to remove the tape, thereby causing a noisy (and sticky) problem.