You could always try the wide-eyed look "My heavens, where did THAT come
from???!!!!" G BRBR

I could do that pretty honestly as I have by now forgotten precisely where I
acquired parts of my stash. (I know who bought them, of course, but couldn't
swear to where the deed was done.) My sister used to use a similar strategy
for things she threw away because they never got put away - she could swear
that she didn't know where the item was
(but of course she knew that the garbage truck took it from her curb).

My stash is getting pretty serious - getting close to having to be listed in my
will. I keep aiming at stash reduction but not getting ahead of it.
JCT