Got airborne with the biggest hangover of my life. Schweizer 269, 97 hours on my personal clock and couldn't make out why my flying was so rough. Landed in the middle of the field to think things through. It took me five minutes of looking around the very basic cockpit to realise I had left the frictions on.
Never, ever flown in that state since (12 500 hours now) Never touched tequila since either.