How Much is that Doggie. . .?

My boys are generally pretty well behaved. It's true, they really are, and not just compared to Tasmanian Devils and hurricanes but next to actual live children their own age. Put a teacher, an aunt, or uncle (or Tyler) in the room with them and their halos 'ping' over their cherubic little heads.
They are, HOWEVER, also smart little devils and it took them less than twenty-four hours to figure out I'm a fairly ineffectual disciplinary figure when I'm feeding the baby. "Settle Down!" means close to nothing when it's yelled from the couch downstairs and they're destroying the second floor. What am I going to do? Yell at them. . . later. Ooo, we're soooo scared, Mom. Now after a few ill-advised, and unplanned shopping trips over their Christmas Break, they've realized I am also helpless while toting Silas in the baby-carrier. (While the stroller sat idly by at home in the garage. 'Yay' for spontaneity.)
So, after a terrifying whirlwind of a visit to Bath and Body Works I decided to press my luck and hit Gymboree. Before we could leave B&B, we had to find Nick's annoying singing stuffed toy his Uncle Josh brought him from Russia. Luckily Max was just hiding it in his hood so once Nick had cried sufficiently enough to fill his big brother's teasing quota, the toy magically appeared. Then, all the coats had to be turned right-side out and be put back on the right boy. (Honestly, why do the clothes come off in the first place? I swear to you we were in the store for fifteen minutes - I loaded a bag full of soaps and candles, had no wait at the register, and we were done. If I would have actually browsed a bit the boys would have probably been stripped down to their underwear and cooling-off in the sink! That's always the excuse for shedding their coats the second we enter a store and swinging them around like they're flagging down a bull; "But, it's SO HOT!".)
Anyway, we hit the clothes store and all three boys stayed with me pretty well for a few minutes. We were making good progress until, elbow deep in a sale bin of adorable briefs, I realized Nick wasn't with me anymore.

Me- Where is your brother?
Grey - (Giggle) That's what I tried to tell you.
Me - What? When?
Grey - Now. I'm telling you now. Nick got behind those things (pointing to the entire wall).
Me - What things? The shelves?
Grey- Yeah, the shelves. He's inside.
Max - That's why you can hear his toy singing.
Me- How did he get back there? Did you see him?
Grey - It's easy. You just go back there.
Max - Yeah, it's easy. (Giggle)
Grey - We were all back there.
Me - That's grrreat. Go get him before he knocks the whole store down!
Grey - (walking away) I can still hear his toy! (Giggle)

Okay, so a.) How did I miss the fact that all three children disappeared long enough to be behind a wall?! and b.) Why would they do such a thing in the first place? Why, why, why!?

AND, even worse - as we're driving out of the mall:
Max - Mom, see where it says '60% off sale'?
Me - Where? At Gymboree?
Max - Yeah. That's where Nick was.

Um, yeah. He was in the display window of the store! Little faceless child mannequins. . . and Nick - all in a 60% off Winter Wonderland.

It is at times like these when having a poker face might come in handy, but no. Not me. I laughed - hard. Dangit! When I asked Nick if anyone walking by saw him he said, "Yeah, but dey didn't see me." Okay. "Really?" I asked. "Well, maybe dey saw me. But dey didn't care. I tink dey yiked me dere." FANtastic. As long as they liked him. There's something else I didn't think I had to teach them NOT to do. That list is certainly growing.