Her drink was by her side, on the ground, until the lawnchairs lifted and took the people sitting in them next to the van.
"Oh!" She said, when she realized what she'd done. Eager to get set up and asleep, she jogged over to the spot they'd been sitting at, her purse still in hand.
Which meant that when she tripped over the rock and went chest first into her soda cup, her purse, and its contents, went flying.