How can you do this? By participating in this event: (RED)RUSH TO ZERO | Check-In.
How does it work? Like this:
Every check-in at Starbucks and select retailers of Penfolds and Bugaboo during (RED)RUSH will trigger a donation from these proud (RED) partners to help fight AIDS. You’ll also unlock the limited edition (RED)RUSH badge – just make sure you follow (RED) on foursquare! (RED)RUSH from June 1st-10th. The beginning of the end of AIDS starts with you.