I figured out why...

I can't get full sheets to fit on my full bed. UUUH!! DUH!! Because it's a queen!! We bought a new bunkbed for the boys and we bought a full on the bottom and a twin on the top. Thinking we were so smart about it because we already owned a perfectly wonderful FULL mattress. We got the bed altogether and I said, "That mattress isn't going to fit. Oh my word, I thought it was a full mattress but it is a QUEEN. No wonder I kept ripping the corners out of the full sheets." I thought maybe Walmart sheets were just cheap and too small because you know, you get what you pay for!!