In the office this morning.

Coworker A: (to Coworker B) "Got my 1-C-3 free today."

("1-C-3" is key combo one uses to get the "Vanilla Mocha" coffee out of the coffee vending machine we have in our break room. It's the best that's in there. It's also just about the worst possible thing you can drink.)

Coworker B: "Oh yeah?"
Coworker A: "Yeah, they've got this thing on there, sometimes it'll give you the coffee for free, you put your dollar in, put in your selection, and it'll refund you money."
Josh: "That's, like, the most sinister psychological thing I can think of."
Coworker A: "Why's that?"
Josh: "Well, think about it. It's the exact same thing they do with slot machines: it's random, but guaranteed reward, so you have to just keep coming back, no matter how unlikely."
Coworker B: "Do people ever tell you that you just suck the fun out of everything?"
Josh: (sigh) "Yes."