Anders Lund Madsen is a professional comedian. These supplemental notes from the uploader/subtitler:
The reason i didn't translate "Stuper" and "grunt" is because Anders is using them in the Danish sentence, and that is why there is an "Er" in the end of "stup."
The rule really means, "don't swim if you don't know how deep the water is."Since I'm half German (and half Norwegian), I particularly liked these lines:
Brygge = A pier (hope that is right)
Stupebrett = A Tipper
"Dytt" or "dyt" is a Danish slang word, that means hump... But in Norway it means push...
"Get some friends!"
"But I'm German!"
"Then go online!"
Via Boing Boing.
(Re-reposted from 2011, just for laughs).