My friend had a horrible sore throat once, but we smoked from the same pipe anyway.
He passed the lighter over the mouthpiece after every hit, but he forgot one time...
Two days later, I came down with a horrible sore throat.
It was so bad that I can't describe the pain to you.
I had a 6-week vacation planned beginning a few days later, but my wife caught the sore throat, and we both were in serious pain for a week or more. Then, it developed into different symptoms.
We could not possible leave for vacation.
Finally, after 4 weeks had passed, and we were still sick as shit, we decided that we simply had to leave.
We drove 16 hours to get to my parents' house for Christmas.
A few days later, both my parents came down with a horrible sore throat.
They were still sick 4 weeks later when I talked to them, though they were beginning to recover.
That was the nastiest cold I have ever experienced.
And passing it on to my wife and parents was painful...
Next time, I will double-check by passing the lighter over the mouthpiece myself, I guess...