Diplomacy: We’re All the Same Inside. When casting a spell or using an effect limited to creatures of a particular type (such as charm person) or limited when dealing with creatures with particular qualities (such as hideous laughter), you may make a Diplomacy check to let that spell apply without penalty to a different creature type. To do so, you must make a Diplomacy check as part of casting the spell (or action for another effect), and meet a DC of 20+the target’s HD. This does not require an additional action on your part. Monsters which vary wildly from the requirements of the spell or effect gain a +4 bonus to the diplomacy DC (for example, a charm person spell could take effect fairly easily on a monstrous humanoid, while an ooze would be much more difficult).
Disable Device: Sever the Strap. When your melee or ranged weapon attack hits an enemy wearing armor, you may make a Disable Device check against a DC equal to double their current full AC. Enemies can always feel you trying to sever the strap, and never count as flat-footed for this DC. If you succeed, the enemy’s armor functions as having been “donned hastily” until they remove it and then replace the armor.
Disguise: Not the Same Inside. When you are about to save against a spell or effect that you have identified as being keyed to a particular creature type (such as charm person) or possessed of certain qualities (like sharing a language), you may choose to forgo your save in favor of a Disguise check to fool the spell or effect into believing that you do not fulfill its prerequisite, causing it to fail. To do so, you must make a DC 20+ the HD of the caster or source of the effect. If you succeed, the spell or effect fails and you do not even suffer consequences (if any) of a successful save. If you fail, you automatically fail your save as well.
Betcha never thought creature type could be so malleable! Be careful about what spells or armors you allow these skills to work on, though it should simply make some interesting choices in both cases.