Many moons ago, on my first ATC flight at (gawp) Cambridge Airport in a Bulldog. Did the usual naive ar cadet thing and ate the entire contents of a very large lunch bag in under three minutes. Got into an a/c. Then I made my first mistake.
I said I knew what I was doing.
"Fair Enough" said the nice chap next to me, "we'll do some aerobatics..."
...needless to say the ham sandwich experienced negative G's pretty quickly and decorated HM's air farce horror bag pretty quickly...
(almost as bad as spin awareness & avoidance in a C152 aerobat with a dented leading edge that caused it to rotate about twice as fast as normal...not pleasant