GTA SA: Kent Paul pukes in the vehicle and Maccer pees inside it

This happens during the mission Don Peyote.

After the player has picked up Paul and Maccer,
Paul will say that he's not feeling right,
in response, Maccer will deliberately suggest
that he should eat inappropriate food.
As a result, Paul will demand that the
player pull over and he will literally
get out of the car and vomit.
If the player does not pull over,
Paul will vomit in the vehicle,
triggering some interesting dialogue.

After Paul throws up, Maccer tells Carl
to stop the car so he can urinate.
If Carl doesn't stop the car,
Paul will tell Maccer to
"point it out the window".
If Carl does stop the car,
Maccer will get out and
urinate for a few seconds,
before going back inside.