Brianna LaPaglia's BFF Grace O'Malley Sounds Off on 'Hick' Zach Bryan

Brianna "Chickenfry" LaPaglia has a staunch ally in her podcast cohost and BFF, Grace O'Malley ... who recently went off on a foul-mouthed rant about her gal pal's ex, Zach Bryan.

Check it out ... Grace, who cohosts "PlanBri Uncut," appeared on "UpDating" and made her thoughts on her bestie's former flame abundantly clear -- calling him a "hick with a vendetta" and a number of other insults.

The Barstool Sports personality got on the topic of the country singer while lamenting about her own romantic history to hosts Brandon Berman and Harrison Forman ... confessing people on dating apps only ever ask her about the other people in her life -- seemingly suggesting Brianna and Zach, without directly naming them.

When someone from the crowd shouted out the country crooner's name, Grace couldn't help herself and shouted back ... "F*** that motherf***er"!!!

As she continued, Grace said most people ask her to hook them up with tickets ... but GOM made it clear she doesn't "f*** with that guy."

Grace's blunt criticism comes amid Brianna's contentious breakup from the chart-topper.

As TMZ previously reported, Zach announced his and Brianna's split on his Instagram Stories in October. Brianna responded to his post by saying she was really "blindsided" by his decision to go public with the news, proceeding to accuse ZB of infidelity and abuse.

Zach has not responded to her accusations ... instead choosing to focus on his tour and music.

While BL was recently linked to a new mystery man -- she was seen cuddling with a new fella in a TikTok video -- she responded to speculation by stating she has no plans to seriously date again.

She added ... "I'm hanging out with a guy who's going back to Australia; I'm never going to see him again. Am I not allowed to live a little? Am I not allowed to smooch a little?"