Let's face it: there is no escaping this one with any modicum of grace.
A. Food/Beverage comes out the mouth or nose of the effected, and you end up with burrito guts in your hair. Also Funny.
B. Effected tries with all his/her might to not allow such seepage, undoubtedly resulting in some form of physical pain. They're covering their mouth, looking away, and desperately trying to inhale oxygen before Coke bubbles erode the entire inside of their mouth.
#1b. The first breath after you manage to swallow whatever was in your mouth.