And while you're blending the daiquiris, you can visualize 18 years of child support payments coming out of your paycheck (or 19 years if the kid doesn't graduate from high school on time...).
It does put a damper on things, doesn't it?
In 2005, 47% of high school students reported having had sexual intercourse, 37% of them without protection (per http://childstats.gov), so you may be continuing the payments after 18 also, unless the kid gets a job quickly...