I've heard this below joke a few years ago but an old fella in line at the bank today told it to me again..

A man and a woman are sitting beside each other in the first class section of the plane.
The woman sneezes, takes a tissue, gently wipes her nose, and shudders quite violently in her seat.
The man isn't sure why she is shuddering and goes back to reading.
A few minutes pass and the woman sneezes again.
She takes a tissue, gently wipes her nose and shudders quite violently in her seat.
The man is becoming more and more curious about the shuddering.
A few more minutes pass and the woman sneezes yet again.
She takes a tissue, gently wipes her nose and shudders violently again.
The man has finally had all he can handle, turns to the woman and says, "Three times you've sneezed and three times you've taken a tissue and wiped your nose then shuddered violently! Are you sending me signals, or are you going crazy?"
The woman replies, "I'm sorry if I disturbed you. I have a rare condition and when I sneeze, I have an orgasm."
The man, now feeling a little embarrassed but even more curious says, "I've never heard of that before. What are you taking for it?"
The woman looks at him and says, "Pepper."