For this you need to head to the Batcave -> Trophy Room and then keep going all the way to your right till you see the Batman TV Set and to your right there will be a cracked wall you will need a STRONG character for this (Grundy, killer croc, big cyborg, big lex, etc.... any 1 of these will work.) then just proceed to destroy the #$@# out of it lol it's the green glowing object.
Achievement should pop up shortly after...
and as per my guides are recorded off the xbox and not a capture card so the pop up sign won't show up on this video but it will for you.