In any MMA fight there are moments of silence where both corners aren't yelling instructions and the announcers cease their commentary. It is during these few seconds that fans choose to yell some of the most obnoxious and annoying comments.
Like all sporting events, alcohol is sold in abundance and likely contributes to the fans getting rowdy. Let's hope the people who yell these phrases have been drinking a few so they at least have an excuse.
Excuse or not, the fact remains the that all of these are by far the most annoying things about watching a MMA bout.