Yes but not on purpose. I once sold bitcoin to a craigslist user at 10% over the spot price. They paid me via paypal, and it turns out they used a stolen account, so the payment was reverted a few days later. However, I had already withdrawn the money and bought more bitcoin with it, so my paypal balance simply went negative. That meant I had taken money out of paypal which I now owed them back, which is the same thing as a loan -- except I got it accidentally and had already used the money to buy bitcoin. There was no interest on this "loan" either. After not depositing any money into paypal for a long time, they handed my account to a collections firm. About a year later I finally paid them back, but only after bitcoin's price rise more than covered the principle of the "loan." So I made out like a bandit. But the "loan" was not on purpose -- it was a result of someone trying to steal from me.