5th-round pick Daylon Mack learned that the hard way ... because after failing to deliver delicious pastries to his teammates, they stuffed the D-lineman's truck with packing peanuts!!!

Mack recorded the aftermath of the hilarious assault ... showing his ride packed to the brim with the foam popcorn.

In the clip, you can see the stuff spilling out of both sides of his whip ... and just to make sure he got the point, they even filled up the bed!!!

"Who even has the time to put all this stuff up?!" Mack said while surveying the damage.

Of course, 22-year-old Daylon got off somewhat easy ... most teams aren't as nice as the Ravens, and use interior-killing popcorn for the gag.

In fact, we've seen firsthand the kind of damage using the buttery stuff can do ... remember Kenyon Martin?!