Colton Underwood says he would literally hide from his teammates in the locker room during his football playing days ... admitting he was terrified he would get turned on and be outed as gay.
29-year-old Underwood -- who played in the NFL from 2014-16 -- opened up about being in the closet throughout his athletic career in an interview with "Call Her Daddy" ... claiming he went through extreme measures to make sure no one knew about his sexuality.
"I wouldn't shower after practice because I was afraid of getting turned on in the locker room or in the shower," Colton told Alex Cooper.