A horrible, abusive ex-boyfriend of mine was repeating college exams - he'd failed, missed and repeated so many that he was on his last chance, about to be kicked off his course if he didn't pass this time.
He texted me in a panic the day before his first exam asking if I had seen his student ID: it was missing and he needed it. I told him truthfully that I hadn't seen it, as I hadn't seen him in a couple of months. He texted again saying if he found out I'd "done something" to his card he'd find out and "make me sorry". I replied that I wasn't even in the same county, which was true: I was 2.5 hours away, where I lived!
Later that day, a friend rang and asked me to collect some documents from her former employer in the town we went to college in: they had to be posted to a prospective employer and she was out of the country, so I agreed.
Arrived in college town, did errand for my friend, and as I walked out of the post office I spotted a card on the ground: yer man's college ID.
Tossed it into the nearest skip
To be honest I thought they'd let him sit his exams without the card but apparently they didn't
Felt good to inconvenience him so greatly.