The former bantamweight champ also stormed into the cockpit to show the pilots weren't wearing masks.
Cody Garbrandt has "no love" for Southwest Airlines.
The UFC fighter stormed off a flight on Thursday after his two-year-old son was told to wear a mask.
The former bantamweight champ posted two videos of the incident, in which he chases the flight attendant into the plane lavatory.
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View Story"F--- @southwestair got kicked off because my 2 year old son wouldn't put his mask over his face," he wrote. "This coward flight attendant hid his b--ch a-s in the bathroom."
The video shows the MMA star storming down the back of the plane and trying to open the door, while another Southwest attendant tries to hold it closed.
"You gonna hide in there?" he can be heard challenging the staff member.
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A second video then shows the 29-year-old storming up to the front of the plane and bursting into the cockpit, accusing the airline of hypocrisy as the pilots were not masked up.
"Kicking a two year old off a plane ride but your captains aren't wearing their masks, while we all are full capacity sharing the same air!" he wrote "What a joke @southwestair"
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Although Garbrandt claimed he was kicked off the flight, Southwest told TooFab he actually left of his own accord, and was even offered a refund.
"We regret this family experienced any inconvenience during their travel," a spokesperson said. "However, federal law requires Southwest ensure every person age two and over to wear a mask at all times throughout a flight, including during boarding and deplaning."
"In this situation, the Customers opted not to fly on Southwest, and they were offered a full refund of their tickets."
They said Garbrandt, like all customers, had been informed of the face covering mandate "at multiple touchpoints throughout the travel journey, including during booking, in a pre-trip email sent prior to departure, and during a required acknowledgement that is part of the Customer Health Declaration Form and appears during the check-in process."
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View StoryNevertheless, Garbrandt received an outpouring of support from fellow fighters in his Instagram comments.
"Dude out of hand," Urijah Faber wrote. "I like to see any of those people mask a two yr old that doesn't want it."
"Some people 'on the plane' are smart enough and capable/allowed to make their own decisions, based on their own research, intuition, and personal experience... others aren't. Sounds like Gov Newsom runs southwest."
Cheyanne Buys, meanwhile, insisted: "You should of slapped the shit out of him."
"It's funny cuz he was prolly trying to punk you then you checked him and boy actually is in the toilet hiding lol," Deron Winn chimed in.
"Imagine being scared of a little f--king kid not wearing a mask for a virus with 99.9% survivability rate," Nick Newell added.
Coach Mark Henry insisted: "Leave little man alone he's 2. Turn off your tape?! Crazy! We got your back Cody bye @southwestair. United."
Renzo Gracie merely said: "Unbelievable these bunch of morons."
Meanwhile, Derek Brunson insisted the fleeing steward was actually "the dude from impractical jokers". "Y'all ain’t slick," he added.
Meanwhile, the CDC has made their requirements clear on masking wearing during air travel, which you can view here.