Lane Kiffin -- USC Gave Me $500k for My House ... But There's a Catch

What USC giveth ... it can taketh away ... and in the process it could maketh its head football coach homeless.

Coach Lane Kiffin is reportedly raking in more than $2 mil a year. TMZ has learned ... USC wanted Lane so badly, the school gave him a $500,000 loan toward the purchase of an insane $5.5 million mansion in Manhattan Beach.

Now here's the rub: Under the terms of the loan, if Lane gets fired or quits, USC can demand the $500k back, STAT. And Lane has to pay interest to boot.

USC sucked this year and the buzz is that Lane's gettin' a pink slip soon. So the question -- even though Lane makes a pretty penny, can he ante up a huge chunk of change to stay in his house if he gets the chop at USC?

Lane certainly has a lot to lose because the house is sick -- 7,300 square feet, 6 bedrooms, 7 baths and a saltwater pool with a spa. It's the perfect place to reflect on how the hell he let UCLA dominate his team and injure his star quarterback this past season.