A Magna Glacier Point "mountain bike"
. There's nothing quite like the low end model of a X-Mart brand bike. The brakes were an experience all their own. Stopping was something they sort of got around to doing. Shifting was OK if you didn't mind the chain grinding against the freewheel. I was new to mountain biking, but even then I had the good sense never to take that bike on a trail (not even a rails to trails MUP). I sold it after owning it two months and used the money to buy a 17 year old Nishiki Ariel and a 17 year old Hoo Koo E Koo for my son. Both of those made it to the MTB trails.
Worst road bike was a Murray I picked up at a garage sale for $12. I soon found out, I overpaid. The farthest trip I took on it was three blocks before the chain jammed. I stripped it for parts and junked the frame.