EASY: unusual landings or takeoffs
EXAMPLE: I once saw a Cessna Caravan land, and keep the nose wheel off the ground until the thing was practically stopped.
FAVORITE: I watched a Lear-35 take off, he did a mild rotation, built airspeed for a few hundred yards, then brought the nose about 25 degrees up! Climbed like a bat outa hell! Then I heard on the scanner for departure 'Lear ****** at four thousand two hundred for four thousand'