Q: Why did the raisin go out with the prune?
A: He couldn’t get a date!
In this joke “to go out with” means to date someone, that is, to begin a romantic relationship. Couples might go out on a date to a movie or go out for dinner on a date. (Date also means the day, month and year: today’s date is Sunday, January 11, 2015… English can be confusing.)
This joke is funny because it plays on the multiple meanings of the word date. The raisin went out on a date with the prune because he couldn’t get a date (an evening out with someone special) with a date (the fruit).