Oh, that's hilarious! Kramer's got his own beat, I tell you. The intern part that I did see was toward the end, I believe, when he was going to leave. Kramer kept opening the door over and over.
Oh, here's the lines, thanks to the site you posted:
(Kramer slams door)
(Kramer opens door)
Kramer: Well, you're still here?
Darren: I haven't had time to leave.
Kramer: Well, I haven't changed my mind.
(Kramer slams door)
(Kramer opens door)
Kramer: Well, you are a tenacious little monkey. Alright, I'll do it. Kramerica industries lives! Let's get back to work!
Kramer's got his own beat, I tell you. 
The intern part that I did see was toward the end, I believe, when he was going to leave. Kramer kept opening the door over and over.