"You know you're commiting a crime! That mask is not yours! I've used this mask for 35 years" - that's what Octagon is basically saying.
More context:
There was a big story in Mexico where Octagon, the original, went to an autograph signing of Octagon Jr. Keep in mind he hates that AAA is using the gimmick but not him anymore. He yelled at him and ripped off Jr.'s mask, and had someone recording it for Facebook. Not once did Jr. respond verbally and physically and Octagon knew he wouldn't and exploited that. Most wrestlers have responded very negatively saying Octagon acted unprofessionally. Some fans were sympathetic because they'll be sympathetic to the guy who was the original with the character and a longtime legend.