Here was the situation. A particular team in a particular sport drove the length of the field on a hot early October day only to be stopped on 4th down during a 13-15 play drive (I can't remember which it was over 20 years ago). I went to the sideline and guzzled down a couple cups of Gatorade and on the second play of the drive the other team got a turnover that forced me back onto the field with a full stomach. They then went on a 8-10 play drive and on the 9th play I puked on the field and came off for a sub. I went back in the next play.
So a combination of heat, fatigue and a full stomach. Does that make sense?