When you cram an unusually large amount of people into a car/truck.

Word derived from the way Mexicans can fit like 20 people into a pick-up at one time.
There were fourteen of us that wanted to go so we had to spic pack Peter's truck.

Billy: I had 9 people in the back of my honda last night.
Chris: Man you were spic packin.
by Spic Lover May 23, 2006
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