Q: Why did the raisin go out with the prune?
A: He couldn’t get a date!

Explanation:  Raisins are dried grapes.  Prunes are dried plums. Dates are just dates.  All three are fruits.

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).