Let the climbing begin

I hear stories from moms all the time about their little kids (mostly boys) attempting all sorts of climbing feats.  I am sure Luke's climbing adventures are no crazier than most kids', but since he is my child, I think they are quite creative and worthy of some blogging press.  Last Friday night I was vacuuming in the basement.  Ben was sleeping and Luke was playing upstairs.  I didn't hear him for a while, so I yelled up to him, "Luke, where are you?  You okay?"  (I start to think maybe I shouldn't be downstairs vacuuming while my 2 year old is upstairs.  What are the parenting 'rules' on this kind of thing?  Are there stories where kids are left alone upstairs and they die or get seriously injured?  How old is old enough to be left upstairs while mom vacuums downstairs?)  I heard his response from the kitchen, "I'm big, mom."  Phew, he's alive and well.  I yell back up, "You are big, Luke.  What are you doing?"  Luke says, "I'm a big boy up here."  Hmmm, did he throw in "up here" at the end of that sentence?  By "up here" does he mean he is a big boy just because he is upstairs?  Is that just his 2 year old language, or is he "up here" somewhere he shouldn't be?  I thought I should check him out.  I walked upstairs and found him on the cupboard - quite cleverly he got there I'd say.  He took his step stool from the bathroom, then stepped on the two drawers he opened.  So the creative climbing has begun.