haha, you just reminded me of when I was a teen (mind you I have not changed dimensions or size since I was 13) I knocked a hole in the wall in a closet that went to a hidden area under the attic stairs. I specifically made the hole to measure 12" x 12" and made a little door for it with a magnetic catch. This was all so if my parents ever found my hiding spot they wouldn't be able to get their asses inside. Not that they were fat they were just both bigger and taller than me.  It took them 8 months before they found it. lmao Oh and last time I was back there I went inside for old times sake. It's awesome fitting into places :)