[Beach Party - Sun-A-Way Stand]

Well, that basically proves it: this guy Dr Valiance is just a part-time worker who got roped into helping out at this stand. Probably got, like, three minutes overview of the product before being told to give out free samples. Explains why he seems half-knowledgeable and half-uncertain about what he's saying.

Anyway, after putting on the sunscreen, she sits in the sand waiting for it to set so that she can do other things, like get into the water or watch all the...

Thirty-seven minutes later

The places that begin burning first are her shoulders. After all, that's the place that most consistently gets sunlight.

At first, she has no idea what's causing it. Stinging, itching, burning sensation. As more and more of it starts burning - her back, her arms, her knees, her upper neck - she notices a particular trend: it's not happening under her swimsuit. Or in certain body parts that would be naturally shaded. She hasn't done anything that would...oh! That sunscreen! She thought for sure she had no allergies, but...maybe a new one developed?

She looks around for where the stand was in relation to herself.
There!

Marin pushes herself through the crowds to get back to the stand. "Hey, I thought for sure I didn't have any allergies," she says, "but, um...what was in the sunscreen? I think I've got some allergic reaction to it." As evidenced by the rashes.