Something new to add to the list of things you're not allowed to say or do on an airplane: sneezing and then apologizing by saying you were in Africa. Not. Cool.
Why? Well because then the plane gets grounded for two hours and you waste everyone's time and money over your tiny (albeit funny at the time) joke. According to various reports, a passenger on a flight from Philadelphia to Punta Cana in the Dominican Republic sneezed on the flight and apologized before adding 'I've been to Africa!', which resulted in the below scene once the plane landed.
Medics later confirmed that the man was Ebola free and upon investigation it was found that he'd never been to Africa. Apparently he got his ass sent right back to the US to be checked again, which is probably just enough karma for pulling this level of joke when everyone is bricking it about dying.