If you wanna see some freaky [censored] put hardcoe mode on put the difficulty way up and take the wild wasteland perk, its not a good feeling to get clubbed to death by rolling-pin wielding old ladies :/
Yeah the H2O, FOD and SLP meters stack outside of HCM so when turning it on you die instantly, to solve this simply sleep for 24 hours and eat a lot of food and drink a lot of water before turning it on.