Justin Bieber and Selena Gomez might seem too young to get engaged and married, but perhaps they're already thinking about starting a family. The teen couple reportedly wants to see what parenting is like with a little help from David and Victoria Beckham's big brood.Perhaps Justin and Selena look up to this older celebrity couple because they're proof that Hollywood relationships can last; David and Victoria have been together fifteen years and have had four kids together. Justin and Selena also recently saw 19-year-old Miley Cyrus get engaged, so perhaps this has inspired them to start planning their future together even though they're still so young.According to NOW Magazine, the couple might get a little practice in parenting if Justin Bieber gets his way. He thinks that Victoria and David Beckham should let him and Selena Gomez babysit Brooklyn, Romeo, Cruz, and Harper Seven.Justin is even offering the Beckhams a pretty sweet deal, too. Here's what he proposed:I think the going rate for babysitters is about 10 bucks an hour, but if David gives me some free kick lessons, I am sure we could give him this one.Babysitting the Beckham kids would certainly be a big challenge for Justin and Selena. David and Victoria have one teen in 13-year-old Brooklyn, and Harper Seven is just a baby. However, the kids are big Beliebers, so they'd probably be on their best behavior around the pop star.Perhaps Selena Gomez and Justin Bieber see babysitting as a way to test their relationship—at least taking care of four kids should test their patience. Or maybe they just think that it would be a fun thing to do (the Beckhams probably do have some pretty awesome toys).So what do you think, are Selena and Justin thinking about their future together, or are they just trying to do something that normal teens do by offering up their babysitting services?