Jake Paul has moved on from punching bags -- the Problem Child just used a Soundcloud rapper to hone his boxing skills ... hitting Lil Pump with a vicious body shot!!
The internet star and fighter welcomed the "Gucci Gang" musician on his "BS with Jake Paul" podcast this week ... and about halfway through the episode, Pump asked if Paul was willing to punch him in the stomach as hard as he could -- just so he could experience what it feels like.
Pump was fully committed to the stunt ... even telling Paul he was down to end up in the hospital over it.
Sure enough, once the interview was wrapped ... they went over to the boxing ring and threw on some gloves.
Pump put his arms up as he anticipated the hit ... and Paul didn't hold back, aiming for the liver as he unloaded a fierce punch.
Pump immediately hit the canvas ... wincing and yelling in pain.
"I told you not to do it!!" Paul explained.
Pump was slow to get up ... and while he was probably sore and bruised up for a bit, it seems like he's doing fine now based on his social media activity.
The Jake Paulers are probably hoping this is what it'll look like when he goes up against Mike Tyson in a few months ... but as we previously reported, the 57-year-old boxing legend is hellbent on making him regret taking the fight.