Erg.. Rules forum
I think its been covered well enough that the RAW does not address this scenario at all.
However, I think parts of the RAW can still be applied in a way that makes sense.
Use the
Squeezing penalty of -4 to attacks and treat the characters as if partially in a grapple together, specifically:
Characters do not threaten outside of thier own face
Denied Dex to attacks from outside of thier own face
Limited to only light, unarmed, or natural attacks
All other normal rules for things like being Prone, etc.. apply.
If the Prone character stands up {drawing an AoO}, the rules quoted above about ending movement applies and the character is moved to the nearest legal position {drawing an AoO}
Does this mean its not good to be Prone under an Orc? Of course {he gets -4 to hit for Squeezing and +4 to hit for you being Prone

}
Same rules could be used for bull-rushing two combatants together.
Actualy, I think I like this rule better than the 'mystically cannot enter' rule
