Stacking boxes is the female alternative to crossing swords; when two girls who are friends have smashed the same dude.

This is generally looked down upon for preserving a friendship. Girlfriends should never stack boxes.
"You should smash that fine dude!" - L

"No way! You did, I don't want to be stacking boxes with you" -A
by The Wetdiaper Bandit December 9, 2008
Any instance in which 2 or more boxes are sitting on top of each other. Boxes being any female or anything square for that matter. See definition of BOX
Bert’s Mom was carrying in the groceries and fell on a hot pocket box, therefore making a stack of boxes.

There are multiple stacks of boxes in the warehouse
by BertsMoM July 8, 2006
A group of stupid girls, generally characterized by being loud and irritating, possibly ugly as well. Draws from the slang term "box," for a vagina.
Jason: So yeah, all those random drunk girls just bust into my room and I had no idea who they were. It was like 20 minutes before I could herd that shit outta there.
Ryan: What a stack of dumb boxes.
by Fitterer May 1, 2005
It usually takes about 4 shots each to get women to box stack
by Yogilicious October 13, 2015