Just call her sugar mama!

Sofia Richie stepped out to do some holiday shopping in Malibu yesterday, and she left boyfriend Scott Disick at home for the outing. Perhaps she just didn't want to pay for his purchases? Radar reports that the 19-year-old model foots the bill for basically everything in their relationship, and the bad boy reality star is loving his free ride!

"Scott has barely paid for anything since they started dating. It’s pretty sick. Whenever they’re out to dinner she’ll whip out her Amex when the check comes, and Scott doesn’t have a problem with that," a source dished to the site.

We doubt her Adidas paychecks are covering their lavish lifestyle, so it seems they're putting it all on her dad Lionel! We have to hand it to LD... he has a knack for dating chicks with access to a ton of dough!