Well... your system is probably pretty soaked at this point, and for a urine test, it would take you a good long while to get clean, 30-60 days based on body size/type, amount of reefer smoked, and potency. Since your dad's a doc, he might stand right there and watch you, keeping you from substitution.

Blood tests don't go back as far as urine tests, but there's really no getting past them. If it's been four days since you smoked, I'd say that you're probably going to get caught, and will have to face up to the consequences.

Sorry, hon.