Chris Pratt Punches MMA Fighter In Stomach, 'Happy Birthday!'

What does Chris Pratt give his friends on their birthday? STOMACH PUNCHES!!

That's how he celebrated with his pal Adel "Kyokushin" Altamimi -- the pro-MMA fighter who Pratt walked to the cage at Bellator 214 back in January.

Pratt and Adel are close friends -- and to celebrate Adel's big 30th birthday, his training partners at Jay Glazer's Unbreakable Gym in L.A. handed out a flurry of body blows!

It's a birthday tradition at the gym -- hold the cage, flex your abs and everybody gets a shot!

Among the gift-givers ... Chris, Jay and ex-NFL player Nate Boyer.

As for the birthday boy, he's got a pretty amazing story -- he was born and raised in Iraq and was contracted as a convoy driver for the U.S. Marine Corps.

During his service, Altamimi was captured by Al Qaeda and was threatened with death -- until he was saved by a group of U.S. Marines.

After the rescue, Altamimi moved to the U.S. and began his MMA training -- where he became close with guys like Jay Glazer and Chris Pratt.