She asked me to help with her psychology experiment, and I thought "Yeah, fine, done things like that before, how hard can it be?", t00bed along to the room, filled out the questionnaires, did everything she asked me to, all good...
Then she gave me ten minutes' warning to give a totally impromptu five-minute speech on a subject of my choice.
I am Not Good at impromptu speeches.
I panicked, dried up completely, and was forced to leave the room in shame.
I really, really wanted to help, and now I feel really, really bad about messing up the experiment and forcing her to find someone to replace me.