Tension release. Also, when cursing out officials, fresh breath is a must.

Because chewing tobacco is prohibited.

Tension. Back in the day, you'd see guys smoking or using chewing tobacco on the sidelines.

Its supposed to relieve stress because coaches are always anxious of what will happen

it's hard to yell/scream at players and referees when your throat/mouth is dry. chewing gum helps lubricate your throat/mouth thus making yelling/screaming more comfortable and effective.

For relaxation.

Because, it keeps their mouths fit!

If their jaws aren't moving, they don't feel like they are earning their salaries...so they chew.

tension keeps there mouths from not getting dry cuz they are alwayz yellin

There are lip readers in the stadium with binoculars.
Chewing gum confuses them. Coaches are very good at
TALKING and CHEWING gum at the same time. TRUE

Cause chewin gum is cool. What, you don't chew gum? Get with the times dude. All the kids are doing it.

Nerves. Your livelyhood (unless you're volunteering) is in the hands of kids. I usually click my pen on the sideline. I don't like gum.

Because its better than chewing on your toungue!