Have you been in a situation where the two lucky men were going to have fun with the woman. Then while the woman is riding your face, you feel the other guy sucking your cock? Did you "carry on" or stop?
No. But since you started the thread with that, the obvious question is; has this happened to you or, if not, is it something you wish for?
If you are doing a dp you have to be prepared for cocks to touch or even a Gb. Either way if a guy starts to touch are blow me if still in it