Perhaps the logic here is that if you buy bags for your vacuum cleaner, then you are likely to be a breast-pumping female???
I suppose that if you vacuumed most of your kid's Lego pieces up and filled up your vacuum-cleaner bag (thus needing to buy new vacuum-cleaner bags) -- then you might want to placate the kid by buying more Legos?
How about you guys -- have you come across some such wacky suggestions?