KSI Clowns IShowSpeed Over Wardrobe Malfunction, More Like 'I Show Meat!'

IShowSpeed might never live down his infamous wardrobe malfunction ... 'cause even KSI got in on the jokes when they met up on Thursday -- calling him "IShowMeat" right to his face.

The popular internet personality made headlines after accidentally exposing himself while playing Five Nights at Freddy's last month ... and despite his constant pleas, thousands of people -- including his followers, haters and even his own family -- have called him the cruel nickname ever since.

The trolling didn't stop when the two YouTube stars linked up for a training sesh earlier in the day ... 'cause when Speed started talking to his stream audience after the workout, KSI dropped a savage line.

"All right, chat ... he always calls me IShowSlow," Speed said ... before KSI interrupted.

"IShowSlow, IShowMeat, what else you showing?" Logan Paul's Prime business partner joked.

"What did you just call me, bro?" Speed responded ... staring into the camera in disbelief.

When KSI doubled down -- even taking it a step further with a super NSFW iteration -- Speed did his signature dog bark right in his face before dissing his beard.

It's been a difficult few weeks for Speed ... after taking a few days off from streaming, he opened up on the mental challenges he faced as a result of the viral malfunction.

As for the workout, KSI showed he's been training hard for his October fight against Tommy Fury ... but it was Speed who lived up to his name when it came to sprints.