Why did someone throw up in the pool?

Excellent question from a 3 year old at the dinner table.

Z: They were probably sick and could not get out of the pool in time.
S: They were sick and couldn't get out of the pool to go home and throw up in the Tupperware.
Z: Exactly.
S: But why didn't they puke in the Tupperware? Why throw up in the pool?
Z: They were probably too sick, or didn't know they were sick.
S: Because you don't throw up in the pool. You throw up in Tupperware.