Having the fire/rescue trucks follow us back to the gate after our ORD-LAX flight had to return to ORD because of a malfunctioning engine. This was also my first time having to return to the departure airport after already being in the air.
Sat across from a group of college age guys on an early morning flight from ORD to LAS, it was obvious that they'd already started their drinking before they'd boarded. One was barely functional by the time we landed in LAS and of course had to get up during taxi to use the bathroom. He couldn't figure out that the bathroom door was locked, so kept fiddling with the latch and finally resorted to banging on the door.