wrongway

When people are saying that all they used for theyre plants fert is urine.... do they mean, human urine? is this safe? :P how much do you use? can this be used without other ferts? Please tell me everything about use of urine, besides the fact that its liquid and smells like ... uh urine... and that its not good to drink so why would we smoke it?
confused,
halfbaked,
wrongway