Or punched it right... Which reminds me, I'm gonna break a board with a punch on Wednesday. Don't tell me I'm not, because I failed twice in a row last time (ouch). This time I have the technique down though
Good luck. I showed my webcam around my old room before I moved out, I had nearly 16 holes punched into the wall, a few of them which went through the 2x4s. Fun times. Amazing how agitated I get when moderating children on this site sometimes... oh and when I spend 5 hours a night wiping on a boss in WoW... but w/e.
It is concrete, don't believe me? I'll have Tnuckvirp + Jay both have a nice wee feel of my wall while they're up here. Also, the reason i punched it is personal and im not gonna post it on the interwebz but all i'll say is... domestic.
Even if it is concrete, its not solid concrete, its a sheet of concrete, can't really fill it. Could use a drywall kit I guess, or use a patch on it, etc. but filling it would be out of the question in the traditional sense.