Here’s a grubgirl tip. Every July 11, 7-Eleven (7-11), the convenience store, gives away a free 7.11-ounce Slurpee.
There are only a 2-3 locations listed in downtown San Francisco though I could have sworn there were some out near Western Addition.
You should only go there if you’re close by, though, or are planning to change your appearance every trip you make. 7.11 ounces is pretty small, but then again, you just need one sip to get a brain freeze!