What are the dumbest investments you've ever made?

I'm far more conservative than I used to be so my long-term funds are now mostly index funds. But here are some dumb investments I've made from ancient history.

2011-2015 (these stocks dont exist anymore)

AZC -- owned the massive Rosemont copper mine in Arizona but always ran into regulatory issues and never drilled... eventually bought for pennies by a Canadian company that still wasn't successful in getting approval

AVNR -- small biopharma that developed Nuedexta that treats PBA -- uncontrollable laughter. My friend got me into this and I sold for a loss after one of their many negative drug events. I remember Martin Shrekli shorted this at one point. It actually had a good ending with a premium buyout from Otsuka in 2015. I just didn't have the conviction--I invested in a story I didn't 100% understand.

2016

"CBL" I made a poorly informed private investment in an upstart sports league called Champions Basketball League (I just wrote a blog about it in my profile if you want a quick dumb read). Basically, it was supposed to be a summer league of ex-NBA players but Ice Cube's Big-3 ate their lunch. They never played any games.

Not sure if dumb or just didn't work out: holding TWTR for years with $30's cost basis and selling for a small loss before the Elon buyout drama played out. holding china tech mega caps for years and losing money while they became the worst shareholder environment ever.

Yeah I did dumb stuff in my 20's. Tell me about your worst plays.