I had a deal three days from closing. Three days. The buyers had already scheduled movers, the sellers had packed up their entire garage, and I was mentally spending my commission on a very overdue vacation. Then the buyer's lender calls and casually mentions they need "just one more document" to clear underwriting. Turns out that one document revealed my buyer had co-signed a car loan for their cousin six months ago and conveniently forgot to mention it. Debt-to-income ratio? Destroyed. Loan approval? Gone. I spent the next four hours on the phone trying to salvage things while my seller screamed at me like I personally handed their buyer a pen and said "hey, co-sign this Dodge Charger for your deadbeat relative right before the biggest purchase of your life." The cousin, by the way, had already missed two payments. Two. My buyers are now renting month-to-month, my sellers relisted at a worse time, and I have developed a twitch whenever anyone mentions family members needing "a small favor." I don't even have cousins and I'm mad at them.