Logan Paul Used As Ryan Garcia's Human Punching Bag, 'F*** Me Up!'

Here's a sight that'll make KSI VERY happy -- Logan Paul took an absolute beating from a real deal boxing star on his podcast ... and the video looks painful as hell!!

20-year-old Ryan Garcia -- a 17-0 rising boxing star -- turned the social media megastar into his own human punching bag on the "Impaulsive" podcast on Monday ... as part of the Body Shot Challenge.

If you can't figure it out ... the Body Shot Challenge is when someone tries to punch you as many times as possible (usually wearing some sort of padding).

Paul volunteered to be Garcia's guinea pig ... but the dude was clearly shook.

"I am f*cked. I am SO f*cked," Paul says before taking 20 straight punches to the gut and falling backward.

BTW, Garcia's known to be a heavy hitter -- he's knocked all but 3 of his opponents. But, Logan takes the hits like a champ, though ... and even takes one WITHOUT the padding!!