Or more appropriately... if your spouse/SO asked... would you??

I consider myself to be very open minded and am sooo very willing to try anything once... so this is the question I pose to all the wonderfully sexual people here:

If you were asked by your partner to participate in a 3 some, with someone of your gender being the 3rd party would you be willing to do so? I don't mean participation as "watching, observing, and limiting your contact to only your partner". I mean participation as more of a hands on.. enjoying the 3rd party yourself type of thing

Would you be willing to allow the 3rd party to pleasure you orally? Would you be willing to do the same for him/her? Would the fact that your partner desires you to do so, encourage you? or would it make no difference? Would you deny your partners desire?