Popping in through a door or into an office cubicle so fast that the occupant therein never hears you coming and loses bodily fluids (or at least is really startled). Think of how Kramer always entered Jerry's apartment on Seinfeld.
I'm so tense at work because I never know when my boss is going to come kramering into my cubicle and make me spill coffee all over the keyboard!
A person who you needin your life to lean on. They are normally the nicest people but they will roast you in no time. They are caring, selfless, and smart even though they might not know it.
Jack: Hey Jill, what's the difference between a black man and a kitchen table? A kitchen table can support a family!
Shaniqua (in background): Hey! That's racist!
Jill: Oh shit, you just had a Kramerian slip.