I told my admittedly at the time very young daughter that trampolines were called that because in "the olden days" they used to be leant on their sides to be used, which because she is young and I am Dad she believed completely.
Years later when she was 15 she recalled this piece of information totally out of the blue and informed her young niece, sadly she wasn't joking but not being quite so gullible my niece said "Yeah but surely you just fall onto the ground" the look on her face was priceless as the penny finally dropped.
Edited: 04/03/2013 at 16:38