Indestructible, being constructed of such materials and in such a way that much abusive handling cannot cause considerable damage, if at all.
Dude, your car just drove over a landmine and you survived! That thing's bombproof!!!!!
In rock climbing
, an anchor (or series of anchors) that is so sturdy, it is essentially impossible for it to fail.
Make sure your anchors are bombproof, dude, otherwise you'll probably die, because you're a crappy climber. And you're a bad person, too, so you'd probably burn in hell for all time.
An object that is apparently indestructible. Often used in reference to anything that has been overbuilt or had additional material welded to it.
Mike's new BMX is bomb proof!