Grandma, Daddy said you're inept

SO, my son goes to pre-school with the child of a certain recently and publicly disgraced x-politician, which in my state could be any number of people, but just to not cause that family any more grief, in case they google themselves I won't be using their real names. Anyway my mother sees a Valentine's day card rather poorly and haphazardly draw by the progeny of said politician and in front of my son says, "That poor Fake Kid's Name, they sure do have problems," and as if this were some Meet the Focker's-esque family comedy my son blurts out, "Fake Kid's Name really has problems!?! What grandma, Fake Kid's Name has problems?!?"
Panic mode ensues and we come up with some cover lie that he buys and stops repeatedly saying, "Fake Kid's Name really has problems!?!" It was like he was really curious about what problems Fake Kid's Name had.

Now the kids not only pass information on to their parents, unfortunately it's a two way street and your kids will rat you out to your parents, or misconstrue something you say and pass that along to the grand parents and get you in deep shit.
This has happened to me twice, but at this time I can only remember the details of the last time it happened.
My son collects comic books, which I store for him some where that his little brother can get at, and where he has to ask me to get them out, so I can keep track of them while he's using them. I managed to keep all of my childhood comics to pass on to him, and with a little luck I'll be able to keep them in good condition until he's old enough to take care of them on his own, and who knows maybe pass them on to his first born.
So he's going away to maternal grandmother's for the weekend, and the week before every day, several times a day he's asking me if he can bring the comics to grandma's house, so at first I'm like no you can't, that's not a good enough answer, "Why?" "Well because Grandma's going to be very busy watching you two boys, and you guys will have toys spread out all over the house and it will be too hard for her to keep track of the comics, and to make sure you little brother doesn't tear them or draw on them."
Now by the 20th time that answer starts to be, "I'll tell you why, Grandma can't chase after you boys all weekend to protect your comics from your brother," 40th time, "Grandma's not so good at keeping track of stuff," 6 millionth time, "LOOK GRANDMA'S NOT SO GOOD AT TAKING CARE OF STUFF, ALRIGHT I DON'T WANT YOUR COMICS DESTROYED!"
Ring, Ring, "Grandma, Daddy said I can't bring the comics because you're no good at taking care of stuff!" Just fucking great, how do you explain this one away, basically not worth the bother, and frankly she's not good at keeping track of things and taking care of stuff, but I tried hard and long to keep my real opinion under wraps, but that little punk broke me like a first timer in central booking.