As Cbc has said MORE than once.
"Tsukasa"
There was one I read in a joke book which was three pages long. The punchline involved the ambiguity of an ordinary word with two of it's most common meanings
...Geddit?
Knock Knock. :]
Dwayne
Dwaaaayne the bathtub, I'm dwowwningggg!
Rye has the worst collection of knock knock jokes in the history of everything. I suggest you all flee now before she destroys your soul.
Knock Knock!
Who's there?
Impatient Cow!
Impatient--
MOOO!!!
This writer named Steve decided to start writing erotic novels, except he had a little problem, he had never had sex. So then Henry asks him, "have you ever had sex?" and Steve swiftly replied "No, but I have a desk"
It actually makes sense in Norwegian, but it's equally funny in all languages.