27-year-old McKee and 26-year-old Pico stopped by the TMZ offices this week and sat down with Babcock for the "TMZ Sports" TV show ... to promote their Bellator 286 scraps, going down Saturday night in Long Beach, CA.

During the convo, the guys, friends for nearly their who lives, ranked #1 (A.J.) and #3 (Aaron) challengers in the featherweight division, were asked if they'd ever fight each other in a sanctioned bout.

The short answer ... nope.

"No, we wouldn't do it. We've talked about this before and we said this, 'Listen, if it ever came down to that, it's gonna be years and years from now. Those zeros better add up,'" Pico said.

Aaron continued ... "I'm gonna say 'Hey AJ, is your son gonna be taken care of for life? Are you gonna be taken care of? I'm gonna be taken care of?' But right now, there's so many people for us to smash. I just don't think so."

McKee then broke down the history of their friendship ... and it's not just two guys who occasionally train each other -- they're basically family.

"You gotta go in there with the intent to hurt your brother. Legit known each other since we were 3, 5 years old. Too many fish in this pond."

Aaron chimed in ... "It goes deeper than that. We've been friends. My mom would go and pick him up from his house, you know, we'd all have sleepovers. My dad talks to his dad a lot."

So, barring a huuuuuge check, it ain't happening.

"It'd have to be a lot of zeros. A lot of zeros. His family's taken care of, my family's taken care of. After, we can sit by the pool with a drink and just laugh," Pico said.

There's much more ... we also talked to the fighters about their 286 matchups (McKee's fighting Spike Carlyle at lightweight, Pico's fighting Jeremy Kennedy at featherweight).

Pico also told a touching story about his early career struggles ... when the prospect, an accomplished wrestler AND boxer, lost two fights in a row (Aaron hasn't lost since).

A win Saturday night in LBC could earn Aaron a title shot ... and complete his comeback.