Has that word "interrobang" been around for a while?
Does the punctuation work backwards!?

perhaps these will suffice?!

http://www.worldwidewords.org/weirdwords/ww-int1.htm
http://en.wikipedia.org/wiki/Interrobang

since ?! is a conventional substitution for the real deal, I don't think they work as well backwards - I've always used that to represent shocked incredulity, as in: I can't believe you would do that!?
as pointed out in the 2nd link above, "interro-bang" is itself suggestive of an order.