Another mystery

A few weeks ago I asked #1 and #2 if they needed socks or underwear. You know that conversation that goes like this:

mmmmm, you have a lot of holes in those socks
yeah, I like that my toes stick out and I get good traction
oh, okay (mother has to ramp up thinking here) but don't you want to slip on the hardwood floors?
yah, I could use some new socks

that was with #2

Conversation with #1:

do you need new underwear?
no.
are things getting too tight?
no.
do you have enough?
yah.

So here is the mystery...we are packing for a visit to Grandma's house (over the river and through the woods and over the mountains and over more rivers....). I ask #1 to get 3 pants, 1 shorts, 6 shirts, 1 pj, 6 underwear, 6 socks. I got the pants, shorts, shirts, pjs. I hollered at him to get him to get his underwear. The child says, "Well, I only have 2 pair." Mother's mind implodes with the word "eeeeeuuuuuuuuu!" echoing in her brain. Where do they go? I know the dryer eats socks? does it have an adolescent boys' appetite and eat boxers too?