Here's an idea:
What if, on a hot summer day, a girl decides to cool off by filling a voodoo balloon with cold water, which causes her to fill with cold water as well. However, while she's relaxing, her friend decides to heat up the balloon, causing the water in the balloon to evaporate and turn into steam. This would, in turn, cause the water in the girl to evaporate and make the girl to inflate even bigger than she was before because water expands when it becomes steam.

-DragonBoss96