7-eleven is doing another of its fab, one day only deals. On Bottomless Cup Day you can buy a large slurpee, and then refill it as many times you like, at any (or every) 7-eleven store you see.
The way it works is, at some point during the day (the earlier it is, the more value you get) you buy a large slurpee. When you pay, grab a sticker off the counter of the store, and stick it on your cup.
Now, you need to keep that cup, so rinse it and put it in a plastic bag. When you next see a 7-eleven store, pull your cup out, fill it up, and it's free! You don't need to grab another sticker, but you can.
I'm already imagining the twittersphere filled with #bottomlesscupday and a Facebook competition over who manages to drink the most large slurpees in a day. It does go until midnight, and some 7-eleven's are open 24 hours a day. Find your local stores here.