Leaving someone stranded in an ice storm can cause hypothermia.
John drives a long-haul semi truck and is going through an ice storm when he sees a stranded motorist waving him down.
John wants to react to the motorist waving.
John pulls his truck over just ahead and yells for the motorist to hurry up and get in quickly.
John blows his horn a few times, smiles, and waves back at the motorist as he drives by.
The motorist is thankful that John just saved his life and can't stop telling him how much he appreciates it.
The motorist can't believe John thought he was saying hello and is left to ponder the inevitability of certain death.