I'm really tired of angry old people who don't understand gift cards

A grandparent came into the store to buy a gift card.

"I WANT A GIFT CARD," he shouted. Now, we have a lot of different gift cards with different pictures on them. In particular, we have "Happy Birthday!" gift cards, and of course we just got all of our holiday gift cards. So, my coworker asks:

"What's the occasion?"

"I WANT A GIFT CARD. SO HE CAN SPEND MONEY HERE," the angry old guy yells, as if it's the register jockey who doesn't understand how a gift card works.

At non-Christmas times, when people buy gift cards, I always ask whose birthday it is. And then they look at me like I am a goddamn wizard and ask how I knew it was someone's birthday. And I always say:

"Why else would you be buying a gift card?"

The embarrassment on their faces fuels my soul.