AVIATION
TOMMY (to Aviator)—"What is the most deadly poison known?"
AVIATOR—"Aviation poison."
TOMMY—"How much does it take to kill a person?"
AVIATOR—"One drop!"
ENTHUSIASTIC AVIATOR (after long explanation of principle and workings of his biplane)—"Now, you understand it, don't you?"
YOUNG LADY—"All but one thing."
AVIATOR—"And that is—?"
YOUNG LADY—"What makes it stay up?"