This is the Flux Capacitor wristwatch available from ThinkGeek ($50). The flux capacitor actually flashes to tell the time, and the date is displayed on the time circuit LCD display below the capacitor. Hold on, I'll just copy the explanation while I eat one of the saddest gas station sandwiches I've seen in awhile.
Press the bottom button and then get ready to count lights. Time is divided into hours, minutes first digit, minutes second digit - so it looks confusing, but is very easy to read. (Example: 10 lights, 5 lights, 3 lights = 10:53 - and it repeats). At the same time, the time circuit LCD display will show you the date. But the Back to the Future Flux Capacitor Wristwatch just doesn't tell the time - with a press of the middle button, you can also activate "Time Travel" mode, where the Flux Capacitor will flux and the time circuit will display a random date.
Are you thinking what I'm thinking? "Nobody wears watches anymore?" Besides that. "Something about the sandwich you just ate?" How do you f*** up chicken and swiss on rye so hard? Sounds impossible, right? Yet here I am. And in thirty minutes, moaning in a bathroom stall. I guess I should start hydrating now.
Keep going for one more shot.
Thanks to Whizkid, who you definitely want on your team at bar-trivia. You are going to have to get him a fake ID though.