Do I need to put a comma here?

[human_male]

"Gosh you have a tremendous penis, Human."

This is correct Human, assuming the comma would not be mistaken for your penis, of course.

Just what are you insinuating?

 

[Lauren Hynde]

I do too and, as long as the "name" is replacing a proper name, it should be capitalized, and that applies to "Asshole", Fucks-Dead-Sheep" or Snookum Ookums. It would not apply to something like "Look here, you asshole" because you are not addressing the person as "you asshole"; you are describing him or her."

I disagree.

"Hey, John! How are you?"
"Hey, you! I have a terrible headache. I can't even remember how I got home last night."

By your rule, it should have been, "Hey, You!" - and that would just be... so wrong.

 

[Boxlicker101]

I disagree.

"Hey, John! How are you?"
"Hey, you! I have a terrible headache. I can't even remember how I got home last night."

By your rule, it should have been, "Hey, You!" - and that would just be... so wrong.

You might be right. In the last example, "you" might be a description, with the actual descriptive word left to the imagination. Such as: Hey, you bum" or Hey, you asshole." or other such. It can also be an affectionate descriptive word, such as "C'mere, you."