How 'bout Some Fries Wih That Shake?

Like many stores, ours sells little paper placards for different charities throughout the year. You pay either $1 or $5, and we give you a little paper card to write your name (or anything you want, for that matter) on. We then display all the cards for everyone to see. Remember this. This will come up again in a later post. Pretend you're surprised. Anyway, the charity we're raising money for this month has, appropriately enough, shamrock-shaped cards.
During my shift yesterday, I had a customer who looked a lot like Carl from ATHF. Here. For reference:

When I asked him to purchase a shamrock for charity, he replied, in a very thick and nauseating voice, "I'll buy shamrocks if you tape them on (he gestured to my boobs) and give me a shamrock shake. Heh heh." I kept a completely straight face, looked him in the eye and replied "Sorry, sir. I'm not McDonalds. That's the only shamrock shake you'll be getting. You can find them across the street."
After this, I immediately went to my supervisor and told him that "anytime a customer buys 2 $5 charity placards, we should have to give them a mandatory shamrock shake. And not the kind they serve across the street". I then gave a little demonstration and walked away, leaving him staring open-mouthed at what I just did. Then from behind me I hear "Oh my god. Yes. Please do it."