For me, I'd say when I went to hot topic.
So I was looking for Walking Dead items (doesn't have to do with MLP, but relevant to story), and I suddenly see a Luna plushie.
I casually look around, and grab it from the basket thing it was in, and smoothly put it on the counter to pay.
Reaching in my pocket, the cashier asks me why I'm buying it.
I couldn't really think of anything, so I say it's for my sister.
My face was bright red, and pretty sure he knew I was lying.
After paying, I quickly walked out.
So I'm walking out of the store holding the bag like it's explosive.
How about you guys?