Jonathan Parker caught a kickoff near the sideline with Iowa already down 28-0 and realized he was about to run out of bounds, which wouldn't be a good return. But then he did this:
(GIF via ESPN)
For some reason, Parker thought it would be a good idea to chuck the ball back into play. His teammates were understandably not expecting this sudden decision, and some Tennessee players jumped on the ball.
It was initially ruled that Parker had gone out of bounds before making the throw, but as you can see, the ball was out of his hand before his foot stepped out of bounds.
This led to a little bit of confusion. Tennessee clearly recovered the ball, but it wasn't theirs to recover. Parker's pass was forward, and thus not a fumble, but an incomplete pass. After thinking about what they just saw, the referees realized the right thing to do was flag Parker for an illegal forward pass.
Parker is lucky. Chucking the ball at nobody in particular is almost never a good idea in a football game. It turned out not to be so bad by sheer luck of the rulebook, but the baffling decision summarizes Iowa's horrific performance thus far.