maybe you have heard it before.
Anyway, you get a women with nice boobies to put her forehead up to yours while you are both slightly bent over.
Then the joke..
you say: knock-knock
girl with nice boobies says: who's there
you say: emerson
girl with nice boobies says: emerson who?
you say: emerson nice boobies you have.
bada bing!
heard this from some comedian on a cruise last week.