http://www.justin.tv/ducktoaster#/w/7500251152/184
endless? stream of downtown gaki no tsukai...something.
It's a Japanese comedy show...they do these little contest things where they try their hardest not to laugh or react to the sketch or whatever. Pretty funny.
EDIT: ok. this is pretty fucking hilarious. These 'nurses' are in training and they are now being shown the MRI machine. I haven't laughed this hard in a while.
http://www.youtube.com/watch?v=wGWBUwdu_lc