sow one's wild oats

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb idiomatic, of a male To spread one's genes around by impregnating many females.
• verb idiomatic, of a male To experiment sexually with different partners before a more serious marriage, especially a rich or powerful young male.
• verb idiomatic To indulge in a period of irresponsible behavior.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb live promiscuously and self-indulgently