So in case you were wondering: yes, astronauts do sometimes sneeze in their spacesuits. And no, there’s nothing they can do about it when it happens. The sneeze just splatters on the helmet’s faceplate.
I believe I first read about this in one of those Time Magazine specials I reviewed last year (click here or here).
The thing I really want to know is how the force of the sneeze affects the astronaut’s motion, especially when the astronaut is not wearing a helmet. For example, what happens when an astronaut is floating freely aboard the I.S.S. or some other spacecraft and suddenly sneezes?
I’d imagine the force of the sneeze could have some amusing propulsive effects in microgravity.
Planet Pailly 
The snot method of propulsion.
The propulsive force of a sneeze would be counter balanced by the snot striking the front of the helmet. If the person in the ISS sneezed into their hand or arm, the snot striking their hand or arm would likewise cancel out any propulsive force, although depending on the angles, it could set them spinning. Only if you sneeze the snot straight out might their be propulsion. Although given that it’s coming from the top of your body, again spinning might be more likely.
I can think of worse things that might happen in a space helmet. (I have a friend who used to be a scuba instructor, and he has some pretty gross stories about what sometimes happens underwater.)
LikeLiked by 2 people
Oh, I think you’re right. A full, open sneeze (with no helmet, hand, or arm in the way) would probably send the astronaut spinning. For some reason, I think that’s even more amusing than what I was originally picturing.
As for your friend, I extend my sympathies. I’ve read/heard more than I care to admit about bodily functions gone wrong in spacesuits. I can’t imagine wetsuits are much better.
LikeLiked by 1 person